SCIENCE NOTES For
SSLC
Prepared by: Girish.N, Bengaluru, 9844217032
Contents Chapter 1: Alternate Sources of Energy .......................................................................... 2 Chapter 2: Environmental Issues .................................................................................... 9 Chapter 3: Periodic Classification of Elements .............................................................. 18 Chapter 4: Silicon .......................................................................................................... 32 Chapter 5: Green Plants and Chordates ....................................................................... 36 Chapter 6: Plant and Animal Tissues ............................................................................ 55 Chapter 7: Microbial Diseases....................................................................................... 70 Chapter 8: Types of Motion ........................................................................................... 77 Chapter 9: Heat Engines ............................................................................................... 83 Chapter 10: Nuclear Energy .......................................................................................... 94 Chapter 11: Industrial Inorganic Chemistry ................................................................. 102 (A) Glass..................................................................................................... 102 (B) Ceramics............................................................................................... 106 (C) Paper ................................................................................................... 108 Chapter 12: Carbon & its compounds ......................................................................... 113 (A) Carbon .................................................................................................. 113 (B) Hydrocarbons ...................................................................................... 117 (C) Functional Groups ................................................................................ 124 (D) Hydrogenation of Oils ........................................................................... 128 Chapter 13: Industrial organic Chemistry .................................................................... 135 Chapter 14: Sound ...................................................................................................... 141 Chapter 15: Metals ...................................................................................................... 150 Chapter 16: Electromagnetic Induction........................................................................ 170 Chapter 17: Electronics ............................................................................................... 182 Chapter 18: Behaviour of Gases ................................................................................. 190 Chapter 19: Plant & Animal Breeding .......................................................................... 197 Chapter 20: Control & Co-ordination in Plants............................................................. 208 & Animals .................................................................................................................... 208 Chapter 21: Heredity ................................................................................................... 228 Chapter 22: Ionic Conduction ...................................................................................... 238 Chapter 23: The story of Humans ............................................................................... 244 Chapter 24: Space Science ......................................................................................... 250 (A) Stars & Galaxies ................................................................................... 250 (B) Rockets & Artificial Satellites ................................................................ 253 INDEX ......................................................................................................................... 261
P1: Alternate Sources of Energy
P1
Chapter 1: Alternate Sources of Energy 1.
2
What is the need for exploring alternate sources of energy? a) The non-renewable reserves in the earth are limited which may get exhausted soon if continued to be used at the current rate. b) Use of alternate sources of energy will reduce pressure on fossil fuels making them last longer. c) By using alternate sources of energy, pollution being caused can be avoided. OR There is a need for exploring sources of energy because the sources of energy are depleting and there is a need for their conservation. It is also becoming difficult to discover new deposits. The measures taken to conserving energy sources are not effective.
2.
Name the non-renewable sources of energy. Coal, petroleum & natural gas are non-renewable sources of energy.
3.
Why are the non-renewable sources of energy depleting at a fast rate. The non-renewable sources of energy are being used extensively so their reserves are depleting at a fast rate.
4.
Mention the percentage global use of different sources of energy Source of energy
5.
Percentage of global use
Coal Natural gas
46% 23%
Nuclear energy Hydro-power
20% 7%
Other (renewable)
4%
What are non-conventional sources of energy? Energy sources which are abundant, renewable, pollution free, eco-friendly that do not get depleted are called non-conventional sources of energy.
6.
Name some non-conventional sources of energy. Solar energy, wind energy, tidal energy, geothermal energy and energy from biomass and wastes.
7.
Mention the characteristics of non-conventional sources of energy. Non-conventional sources of energy are abundant, renewable, pollution free and ecofriendly.
8.
How are non-conventional forms of energy useful? Non-conventional sources of energy serve two purposes: a) They supply energy in a decentralized system.
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P1: Alternate Sources of Energy
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b) They help in sustaining a cleaner environment. Mention the differences between conventional and non-conventional sources of energy. Conventional sources of energy
Non-conventional sources of energy
1. Energy sources which are being used traditionally for many years and going to deplete over a period
1. Energy sources which do not get depleted.
2. They are non-renewable sources 2. Usually they are renewable of energy. sources of energy
10.
3. Examples: Fossil fuels, Thermal power plants, Hydro power plants.
3. Examples: Solar energy, Wind energy, Geothermal energy.
4. Most of them cause environmental pollution
4. Most of them do not cause environmental pollution
What is solar energy? The energy obtained from the sun is called solar energy.
11.
What are the two processes involved in the use of solar energy. a) Conversion of solar energy into heat energy. b) Conversion of solar energy into electrical energy.
12.
What is solar constant? The amount of energy reaching per square meter of earth’s atmosphere is called solar 18 constant. It is equivalent to 1.36kw in 12 hours. Its value is 1.5x10 kwh per day.
13.
How is solar energy converted into heat energy? Solar energy falling on the surface of the earth is converted into thermal energy. The heat generated is stored in solar collectors. It is used for purposes like heating of water and cooking of food.
14.
What is a solar collector? Solar collector is a device which is used to store the heat generated by radiation of solar energy.
15.
Mention the uses of solar heater. Solar heaters are used in drying of food grains and vegetables, seasoning of wood, desalination of marine water.
16.
What is a solar pond?
17.
Solar pond is a new technology in harnessing solar energy. It is a large scale solar collector with an integrated arrangement for storage of heat energy. How is solar energy remains trapped in a solar pond? When water is heated by solar radiation, hot water from the bottom of the pond rises and reaches the surface. It loses the heat gained to the atmosphere. This makes the water in the pond to remain at a temperature nearer to that of the atmosphere. The loss of heat is
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P1: Alternate Sources of Energy
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prevented by dissolving salts in the bottom of the pond. It makes the water denser and hence cannot rise to the surface. Thus solar energy remains trapped in the pond. 18.
What is the role of salts in a solar pond? OR Give reason: Salts are dissolved in the bottom of a solar pond. The loss of heat from the pond is prevented by dissolving salts in the bottom of the pond. Dissolving salts makes the water denser and hence cannot rise to the surface. Thus solar energy remains trapped in the pond.
19.
How is solar energy converted into electricity? Solar energy is converted into electricity by using the principle of photo voltaic effect and device called solar cell.
20.
What is a solar cell? A Solar cell is a device which converts solar energy directly into electricity.
21.
Mention the uses of solar cells. Solar cells are being used in traffic signals in some cities, lighting lamps and pumping water in rural areas.
22.
Differentiate between solar collectors and solar cells. Solar collectors Solar collector is a device used to store the heat generated by the solar energy
23.
Solar cells Solar cell is a device used to convert solar energy directly into electricity.
What is biomass? Biomass includes wood, agricultural wastes and cow-dung.
24.
What is bio energy? Bio energy includes those processes where biological matter such as plant and plant products provide the basis for energy and its conversion.
25.
Mention the advantages of biomass. a) Biomass offers clean fuel for energy. b) It maintains an unpolluted environment c) It reduces carbon dioxide content in the atmosphere. d) It improves quality and water retention capacity of soil.
26.
What is biogas or gobar gas? Biogas is a clean, unpolluted and inexpensive source of energy produced from cow dung. It mainly contains 70% methane.
27.
What are the advantages of biogas or gobar gas? a) Biogas is a clean and unpolluted fuel.
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P1: Alternate Sources of Energy
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b) It helps in obtaining both cooking fuel and enriched manure. c) It is suitable for rural areas where cow dung is available in plenty. Mention the uses of biogas. a) Biogas is used for cooking b) The slurry left behind is good manure. c) It is used for lighting. d) It is used for running small engines.
29.
List two practical uses of biogas in rural areas. a) Biogas is used for cooking b) It is used for lighting c) It is used to run small engines.
30.
Give reason: Biogas is considered to be a boon to rural areas. Biogas is more suitable to rural areas because the raw materials like cow dung, agricultural wastes etc are easily available. It also provides enriched manure which can be used in agriculture.
31.
“Biogas is a better fuel than burning animal dung cakes”. Justify. Biogas is better fuel because: Biogas does not causes pollution, whereas burning dung cakes cause pollution. It does not leave ash behind after burning whereas burning dung cakes leaves ash after burning. It can be used for lighting, running small engines whereas dung cake can be used only for cooking.
32.
How is biomass converted into energy? Biomass is converted into energy by three processes: a) Combustion pyrolysis b) Bio gasification c) Fermentation
33.
What is combustion pyrolysis? Combustion pyrolysis is a process of chemical decomposition at high temperature (upto o 500 C) in total or partial absence of air.
34.
Name the products obtained by combustion pyrolysis.
35.
Fuel gas, ethanol and charcoal What is meant by bio gasification? Bio gasification is a process of anaerobic digestion of biomass to produce biogas.
36.
What is fermentation? Fermentation is the conversion of sugars into alcohol to produce ethane and solid residue fuel.
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P1: Alternate Sources of Energy
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How is bio diesel prepared?
38.
The crude oil extracted from the seeds is converted into bio diesel. What is trans esterification?
6
Trans esterification is the process of conversion of crude oil obtained from seeds of plant into commercially useful fuel. 39.
What is the advantage of using Jatropha plant in making bio diesel? a) Jatropha plant grows in any type of soil. b) It grows in any kind of climate. c) It can be propagated easily through seeds or stem cutting. d) It grows very fast. e) It is not grazed by animals.
40.
Mention the steps taken by government of Karnataka to encourage the use of bio diesel. Government of Karnataka has started schemes to encourage farmers to grow Jatropha in their field during lean periods of agriculture. The seeds of Jatropha are purchased by the government to extract oil. Bio diesel is being used to run K.S.T.R.C and B.M.T.C Buses.
41.
Name two plants that are source of biofuel. Jatropha and Pongamia pinnata (Honge)
42.
What is wind energy? Wind energy is the kinetic energy associated with the movement of large masses of air.
43.
How is wind energy from solar energy? OR Give reason: Wind energy is the converted from of solar energy. The differential heating of the atmosphere by the sun causes air movement and produces wind. Thus wind energy is converted from of solar energy.
44.
What are the advantages of wind energy? a) Wind energy is a renewable source of energy. b) It is eco-friendly. c) It is free and requires no recurring expenses for production. d) The total potential of wind energy is very large.
45.
What is a wind turbine? Wind turbine is a device used for the purpose of obtaining wind energy.
46.
What is wave energy? The energy obtained from movement of large quantities of water up and down in the seas and oceans in the form of waves is called wave energy.
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7
Give reason: Tropical coastline of India, especially the South West coast is highly suitable for establishing wave energy. Due to the blowing of wind on the surface of Arabian Sea, very fast sea waves move to the surface. Due to their high speed, sea waves have a lot of kinetic energy.
48.
Give reason: Wave energy is not feasible. The cost of energy conversion per unit is very high, since it requires many special equipment to be created near the sea.
49.
Give reason: Wave energy is more reliable then wind energy. Since the fluctuations in wave energy are comparatively less then that of wind energy.
50.
What is geothermal energy? The energy obtained from the heat of the earth within 10km from the surface is called geothermal energy.
51.
Write a brief note on geothermal energy. The word geothermal comes from the words geo means earth and thermal means heat. Geothermal energy is the heat from within the earth. It refers to the heat of the earth within o 10km from the surface. It can be used to produce power. It has a temperature of 1300 C.
52.
Name the source of energy which is not directly related to the solar energy. Geothermal energy.
53.
How can energy be produced from wastes? A huge quantity of wastes is generated in cities and towns. It is also generated in sugar, paper and pulp industries.
54.
List the advantages of non-conventional sources of energy. a) Non-conventional sources do not deplete. b) They are renewable sources of energy. c) They do not cause environmental pollution.
Fill in the blanks: 1. Coal, petroleum & Natural gas are non-renewable sources of energy. 2. 3.
Solar energy, wind energy, geothermal energy are non-conventional sources of energy. Solar energy reaches us in the form of small packets called photons.
4.
The amount of energy reaching per square meter of earth’s atmosphere is called solar constant.
5.
Solar constant is equivalent to 1.3kw in 12 hours.
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P1: Alternate Sources of Energy 18
8
6.
The value of solar constant is 1.5x10
7.
The device which is used to store the heat generated by radiation of solar energy is called solar collector.
8.
The device used in drying of food grains and vegetables, seasoning of wood, desalination of marine water is solar heater.
9.
The new technology of harnessing solar energy is solar pond.
10. 11.
First Asian country to establish a solar pond is India. In a solar pond, heat is trapped in the pond by addition of salts in the bottom of the pond.
12.
The first solar pond has been setup in Bhuj, in Gujarat.
13.
A device which converts solar energy directly into electricity is called solar cell.
14.
The principle involved in the conversion of solar energy into electrical energy is called photo voltaic effect.
15.
Plant and plant products are called as biomass.
16.
Plant organic matter is called vegetable matter.
17.
The energy obtained from plant and plant products is called bio energy.
18.
The main component of biogas is methane.
19.
The process of chemical decomposition at high temperature (upto 5000 C) in total or partial absence of air is called combustion pyrolysis.
20.
The process of anaerobic digestion of biomass to produce biogas is called bio gasification. The conversion of sugars into alcohol to produce ethane and solid residue fuel is called fermentation.
21.
kwh per day.
o
22.
The conversion of crude oil from plant seeds into useful fuel involves a process called trans esterification.
23.
The plant whose seeds are used in production of bio diesel is Jatropha, Honge.
24. 25. 26.
Wind energy is converted form of solar energy. The ideal speed of wind for production of wind energy is between 8m to 22m per second. The device used to produce wind energy is wind turbine.
27.
The largest installation of wind turbines is near Kanya Kumari in Tamil Nadu.
28.
The energy obtained from movement of large quantities of water up and down in the seas and oceans is called wave energy.
29.
The energy trapped within 10km of the Earth’s surface is called geothermal energy.
30.
The temperature of geothermal energy is about 1300 C.
o
*****
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Chapter 2: Environmental Issues 1.
B2
Define pollution. Pollution is defined as an undesirable change in the physical, chemical and biological characteristics of the environment.
2.
What are pollutants? Give example. The substance which brings about pollution is called pollutant. Ex: In air, smoke or dust particles is the pollutant.
3.
Give reason: Oxides of nitrogen released during lightning is not pollutant but oxides released by industries and automobiles are pollutant. Human interference causes the same substance to become a pollutant.
4.
What are biodegradable pollutants or temporary pollutants? Give examples. The pollutants that can be made harmless either by quick dilution to a very low concentration or by conversion are called biodegradable or temporary pollutants. They can be degraded by biological activity. Example: Sulphur dioxide librated by combustion of coal will get dissolved in rainwater and become diluted. Sewage produced in cities can be made harmless by suitable biological treatment.
5.
Give reason: Sulphur dioxide or sewage is a biodegradable pollutant. Sulphur dioxide gets diluted with rainwater and becomes harmless. Sewage is made harmless by biological activity. Hence it is a biodegradable pollutant.
6.
Give reason: Sulphur dioxide / Sewage are referred to as temporary pollutants. The effect of sulphur dioxide or sewage remains in the environment only till it is converted into a harmless substance. Hence they are referred to as temporary pollutants.
7.
What are non-biodegradable pollutants? Give example The pollutants which cannot be converted into harmless constituents are called nondegradable pollutants. Ex: Lead vapours released from diesel combustion, can accumulate in the lungs. Insecticide like D.D.T from agricultural fields can accumulate in a pond.
8.
Give two ways in which non-biodegradable substances would affect the environment. a) Some of the non-biodegradable wastes like D.D.T enter the food chain and cause biomagnification.
9.
b) Lead vapours from diesel combustion can accumulate in lungs. Give reason: Lead vapours or D.D.T is a non-biodegradable pollutant. Lead vapours or D.D.T cannot be converted into harmless substance by any known biological activity hence they are referred to as non-biodegradable pollutants.
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10.
Distinguish between biodegradable and non-biodegradable pollutants. Biodegradable pollutant
Non-biodegradable pollutant
1. Pollutants which can be made 1. Pollutants which cannot be harmless by quick dilution or made harmless constituents conversion.
11.
2. The effects remain in the environment only till converted into harmless substance
2. The effects remain as residue in the environment for a long time.
3. They can be decomposed by microorganisms.
3. They cannot be decomposed by any known microorganisms
What is meant by bio-magnification? The phenomenon of increase in the concentration of toxic substances at each trophic level in a food chain is called bio-magnification.
12.
Define air pollution. Air pollution is defined as any human activity that brings about a significant change in the constituents of atmosphere.
13.
Name some serious environmental problems. Acid rain, global warming, depletion of ozone layer and climate change.
14.
Mention the main causes of air pollution. a) Coal combustion b) Diesel combustion c) Petrol combustion d) Smoking of tobacco e) Waste incineration
15.
Explain the various causes of air pollution. Coal combustion: Coal is used as a major source of fuel in several industries. Coal combustion releases sulphur dioxide, carbon monoxide and small amounts of carbon dioxide which are pollutants. Diesel combustion: Diesel is used as fuel in heavy duty vehicles and public transport vehicles. Combustion of diesel releases carbon monoxide and carbon dust which are pollutants. Petrol combustion: Petrol is used as fuel in cars and two wheelers. Combustion of petrol releases oxides of nitrogen, carbon dioxide and lead vapours which are pollutants. Smoking of tobacco: Smoking of tobacco in various forms releases high content of carbon monoxide which is a source of air pollution. Waste incineration: Disposing of city garbage by burning them release carbon monoxide which is a pollutant.
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16.
Give reason: Air pollution is not an outdoor phenomenon but also an indoor phenomenon. Just as various factors outside the house cause air pollution, activities like cooking, cleaning also causes indoor air pollution.
17.
Mention the common air pollutants and their effects. Pollutant Sulphur oxide particles
Coal & oil power plants, oil refineries, smelters, kerosene stoves
Effect on health Bronchial disease
Carbon monoxide
Burning of fossil fuels, emission from vehicles
Oxides of nitrogen
Emission from automobiles, burning fossil fuels, power plants, oil refineries
Respiratory disorders
Ozone generators, aircraft cabins
Respiratory disorders
Poly cyclic aromatic hydrocarbons
Diesel exhaust, cigarette smoke, stove smoke
Lung cancer
Asbestos
Asbestos mines & mills. insulation, building materials
Lung cancer, asbestosis
Arsenic
Copper smelters, cigarette smoke
Lung cancer
Allergens
Pollen, animal skin, House dust
Asthma, running nose
Ozone (O 3 )
18.
Sources
Asphyxia leading to heart & nervous system damage, death
Mention some sources of indoor air pollution. Molds and bacteria, carpets and upholstery, pollen, tobacco, pesticides and fumes from chemicals, dust mites, pets, animal hair and dead skin.
19.
Write some measures that can be taken to control air pollution. Industries must be established away from towns and cities. Emission from industries must be checked and controlled. Regulatory rules related to air pollution must be strictly enforced. Automobiles must be periodically checked to improve the efficiency of engine and reduce the emissions. Use of unleaded fuels and bio-fuels must be encouraged. Educating people to use public transport. Measures must be taken to check air pollution at source.
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Mention some measures that can be taken to control air pollution at source. a) Reducing the use of vehicles for short travel. b) Using car pooling to travel & reducing individual vehicles. c) Installing electrostatic precipitators in chimneys of factories & industries.
21.
What is water pollution? Any change in physical (smell, colour taste), chemical and biological characteristics of water is called water pollution.
22.
What are the causes of water pollution? a) Effluents from industries. b) Accumulation of sewage. c) Extensive use of pesticides & fertilizers in agriculture.
23.
Explain the causes of water pollution. a) Effluent from industries: Waste materials from industries containing enormous quantities of chemicals are released into the nearby source of water like ponds, lakes, rivers. Most Indian rivers are polluted by industrial effluents. b) Accumulation of sewage: Sewage containing vegetable wastes, fruit wastes, animal excreta, human excreta and organic wastes from factories are released into water sources. c) Addition of detergents: Domestic wastes contain a high percentage of detergents. Detergents on reaching water bodies, they cause foaming and reduction in the dissolved oxygen content. d) Addition of agricultural wastes: A variety of pesticides and fertilizers used in agriculture which are non-biodegradable are washed away into water sources.
24.
Give reason: Most Indian rivers are polluted by industrial effluents. Waste materials from industries containing enormous quantities of chemicals are released into the nearby rivers. Hence most Indian rivers are polluted.
25.
Give reason: Domestic waste has a high percentage of detergents. More people are switching over to synthetic detergents than using traditional soap which is biodegradable. Hence the percentage of detergents in domestic waste is increasing.
26.
What is eutrophication? What is it due to? What are its effects? The process of increase in the growth of algae in water bodies due to increase of phosphorous is called eutrophication. Eutrophication is due to high phosphorous content of detergents and fertilizers. Oxygen content in water bodies decrease due to rapid growth of organisms which consume phosphorous compounds.
27.
How is ground water polluted? Pollutants like lead, arsenic and fluoride combine with hydrogen, oxygen, iron and chlorine in water results in poisoning of ground water.
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What is meant by thermal pollution? What is its effect? The release of high temperature effluents from furnace and boilers of industries directly into water sources is called thermal pollution. Thermal pollution destroys the aquatic life to the thermal shock.
29.
What is meant by marine pollution? What are the causes for marine pollution? The pollution of seas and oceans is called marine pollution. It is caused due to condensing of the pollutants after reaching atmosphere, agricultural runoff, oil seepage from tankers and industrial effluents.
30.
What are the measures to control water pollution? a) Industrial effluents must be treated to remove the pollutants. Toxic chemical substances must be eliminated. Acid and alkalies must be neutralized. Metallic compounds must be precipitated. b) Effluents from furnaces must be cooled to room temperature and treated before releasing it. c) Sewage water must be treated to remove suspended particles. It must be aerated and then chlorinated to purify water. This can be reused.
31.
What are the steps taken before releasing the industrial effluents into water bodies? a) Industrial effluents must be treated to remove the pollutants. b) Toxic chemical substances must be eliminated. c) Acid and alkalies must be neutralized. d) Metallic compounds must be precipitated.
32.
What are the steps taken before releasing sewage water into water bodies? a) Sewage water must be treated to remove suspended particles. b) It must be aerated c) Chlorinated to purify water.
33.
Explain the need for treating sewage water. Sewage contains human excreta, animal excreta, detergents etc. They contain disease causing microbes. If sewage water is let out directly into water bodies without treating, it spreads water borne diseases.
34.
What are the causes of land pollution? Land pollution is caused due to throwing cans, bottles and plastic items. Burning or dumping them into open lands. It is also caused by agricultural runoff containing residues of fertilizers and pesticides. Acid rain also contributes to land pollution.
35.
How does acid rain cause land pollution?
36.
Acid rain caused by air pollution is also contributing to air pollution by altering the acidity and fertility of soil. Define noise. Noise is defined as any sound which causes unpleasant effect and discomfort to human ears.
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What are the main sources of noise pollution? a) Gadgets used in home like mixer and grinder. b) Transport vehicles like aircrafts c) Commercial and industrial activities, d) Audio equipment used in social and public functions.
38.
List the effects of noise pollution. a) Noise pollution directly affects the human nervous system, causing deafness, headache, high blood pressure and heart disorders. b) Noise causes behavioural discomforts. c) Noise pollution also affect animals
39.
What is meant by ozone depletion? The reduction of the ozone in the stratosphere is called ozone depletion.
40.
How is ozone layer getting depleted? Depletion of ozone in the atmosphere is due to release of chloro-fluoro carbons (CFC) by refrigerators, air conditioners and aerosols.
41.
What are CFC’s? How do they damage ozone layer? CFC stands for chloro-fluoro carbons. It is a product of industrial processes involved in the manufacturing of insulating foams, solvents, cooling equipments like refrigerators, air conditioners. It is also found in various kinds of sprays (aerosols). The ultraviolet rays from the sun break the CFC in the stratosphere into chlorine atoms. Chlorine reacts with ozone and breaks into oxygen.
42.
What is the effect ozone depletion? a) Thinning of the ozone layer allows high levels of UV radiations to reach the earth causing mutations in organisms. b) In humans, the incidence of skin cancer and cataract increases. c) In plants and animals, it affects growth and physiological functions. d) It affects the population ratio of phytoplanktons causing serious imbalance in the ecosystem. e) In the atmosphere, it affects the natural balance of gases, particularly affecting the carbon cycle.
43.
What are mutations? The sudden change in the genetic material of an organism is called mutation.
44.
What is meant by global warming? Rise in the average temperature of the earth’s atmosphere and oceans is called global warming.
45.
What is meant by greenhouse effect?
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The increase in the atmospheric temperature due to trapping of heat by some gasses in the atmosphere is called greenhouse effect. 46.
What are greenhouse gases? The gases responsible greenhouse effects are called greenhouse gases.
47.
What is a greenhouse? A green house is built of any material like glass or plastic through which sun light can pass. The ground inside gets heated up, warming the air inside. The air continues to heat up because it gets confined within the green house.
48.
Where are greenhouses used? Green houses are used in horticulture to provide warm temperature for growing ornamental plants.
49.
Why greenhouse effect is called so? The warming effect is similar to what is seen in green house. Hence it is called greenhouse effect.
50.
Name the greenhouse gases. Carbon dioxide, oxides of nitrogen, methane and ozone are the greenhouse gases.
51.
What are the consequences of global warming? Global warming has resulted in melting of glaciers, causing an increase in the sea level. Flooding of sea water results in submerging of lands.
52.
Give reason: Global warming affects both aquatic and land life. Global warming causes melting of glaciers, causing flooding of sea water which in turn results in submerging of land. Hence it affects both aquatic and land life.
53.
How is acid rain formed? When oxides of sulphur and nitrogen in the atmosphere combine with water vapour, it forms sulphuric acid, nitric acid respectively. This precipitate as rain, snow or fog. The main source of the oxides is combustion of fuels in the industries.
54.
What are the effects of acid rain? Effects on aquatic life: Acid rain affects all forms of life. It affects egg production in aquatic animals. It alters the population ratios. Effect on vegetation: It can affect vegetation. It leaches the nutrients in soil. The leaves of affected plants develop spots and crack allowing infection. Effect on monuments and buildings: It also affects old buildings and monuments. It damages metals and stone structures.
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Effect on human health: 55.
It causes skin allergies and respiratory problems. Give reason: Acid rain affects population ratio. Acid rain affects egg production in aquatic animals hence it alters the population ratio.
56.
Give reason: Acid rain affects vegetation. Acid rain makes the soil acidic and leaches the nutrients in soil. It also allows pathogens through cracks in affected plants. Hence acid rain affects vegetation.
57.
Give reason: Taj Mahal is a mute victim of acid rain. A large number of industries in the neighbouring areas of Taj Mahal release gaseous pollutants causing the marble to lose its glaze. Hence Taj Mahal is a mute victim of acid rain.
58.
What is meant by radioactive pollution? The pollution caused due to emission of protons (alpha particles), electrons (beta particles) and gamma rays is called radioactive pollution.
59.
Mention the two types of radiation and explain. The two types of radiation are: a) Ionising radiation: Radiations having high penetration power and cause breakage of macro molecules. b) Non-ionising radiations: Radiations which affect only those compounds which absorbs them.
60.
Mention the penetrative power of alpha, beta and gamma particles.
Type of particles Alpha
Blocked by paper, human skin
Beta
Penetrate through skin but blocked by glass or some metals
Gamma
61.
Penetrative power
Penetrates skin and damage cells. They cannot be blocked
Mention the source of radioactive pollution. a) Nuclear power plants b) Nuclear weapons c) Disposal of nuclear wastes d) Use of radioactive isotopes e) Mining and refining of radioactive substance like uranium and thorium
62.
How does radioactive material affect humans? Radio active materials react with biological molecules. It can damage DNA, leading to cancer and birth defects.
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Fill in the blanks: 1. 2.
An undesirable change in the physical, chemical and biological characteristics of the environment is called pollution. The necessary factor that makes any substance a pollutant is Human interference.
3.
Oxides of nitrogen released during lightning is an example of biodegradable pollutant.
4. 5.
An example of biodegradable pollutant is sewage. Sewage is made harmless by biological activity.
6.
Pollutants that can be made harmless by quick dilution or conversion are called biodegradable pollutants.
7.
Pollutants that cannot be made harmless constituents are called non-biodegradable pollutants.
8.
Global environmental problems are caused due to long term effects of air pollution.
9.
The phenomenon of increase in the concentration of toxic substances at each trophic level in a food chain is called biomagnification.
10.
Any human activity that brings about a significant change in the constituents of atmosphere is called air pollution.
11.
An example of an activity which causes indoor air pollution is cooking / cleaning.
12.
Waste incineration releases mainly carbon monoxide.
13.
Any change in physical (smell, colour taste), chemical and biological characteristics of water is called water pollution.
14.
The process of increase in the growth of algae in water bodies due to increase of phosphorous is called eutrophication.
15.
Detergents cause a decrease in the oxygen content of water.
16.
The release of high temperature effluents from furnace and boilers of industries directly into water sources is called thermal pollution.
17.
According to estimates, every human generates six kilogram of trash every day.
18. 19.
Any sound which causes unpleasant effect and discomfort to human ears is called noise. The unit of measuring sound is decibels (db).
20.
Any sound with intensity of beyond 100db is harmful to human ears.
21.
The reduction of the ozone in the stratosphere is called ozone depletion.
22.
The sudden change in the genetic material of an organism is called mutation.
23.
Earth’s mean temperature is said to have increased by about 0.8 C since the beginning of this century. Increase in the heat content is greater in the oceans than in any other source of energy.
24.
o
25.
90% of the possible increase in the heat content of the earth system takes place in oceans.
26. 27.
The greenhouse gases are carbon dioxide, oxides of nitrogen, methane and ozone. The pH of rain water is 5.6.
28.
The main source of oxides which cause acid rain is combustion of fuel in industries. *****
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C3
What is the need for periodic classification of elements? When elements are classified such that they have the same properties, study of large number of elements is reduced to study of few groups of elements.
2. Give reason: Classification of elements on the basis of states of matter cannot be justified. Classification on the basis of states of matter cannot be justified because for example bromine and mercury are liquids at room temperature, they cannot be placed in the same group. 3.
Give reason: Classification of elements as metals and non-metals is justified but not satisfactory. Classification of elements as metals and non-metals is justified because there are more common characteristics in both the groups but it is not satisfactory because each metal or non-metal have completely different properties.
4.
State Dobereiner’s law of triads.
5.
According to Dobereiner’s law of triads: When elements are arranged in the order of increasing atomic masses in groups of three elements, the atomic mass of the middle element of the triad is equal to the average atomic mass of the other two elements. What are triads? Elements arranged in group of three are called triads.
6.
Explain Dobereiner’s law of triads with an example. According to Dobereiner’s law of triads: When elements are arranged in the order of increasing atomic masses in groups of three elements, the atomic mass of the middle element of the triad is equal to the average atomic mass of the other two elements. Example 1: Atomic mass of chlorine = 35.5 Atomic mass of Iodine = 127
35.5 + 127 162.5 = = 81.25 2 2 Average atomic mass = The atomic mass of middle element Bromine = 80 Example 2: Atomic mass of Calcium = 40 Atomic mass of Barium = 137
40 + 137 177 = = 88.5 2 2 Average atomic mass = The atomic mass of middle element Strontium = 88
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In a triad A, B and C, the atomic masses of A and B are 80 and 120 respectively. What is the atomic mass of element C? Atomic mass of A=80 Atomic mass of B=120
A+C 2 Atomic mass of B =
80 + C 2 120x2 = 80 + C 240 = 80 + C 120 =
= C 240 − 80 C = 160 8.
9.
Therefore atomic mass of C = 160 In a triad X, Y and Z, the atomic masses of X and Y are 7 and 23 respectively. Find the atomic mass of element Z.
In a triad of A, B, C elements, if the atomic mass of B and C are 150 and 200 respectively. Find the atomic mass of A.
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20
The atomic masses of three elements X, Y and Z having similar chemical properties are 7, 23 and 39 respectively. a) Calculate the average atomic mass of elements X and Z. b) How is the average atomic mass of elements X and Z compare with the atomic mass of element Y? c) Which law of classification of elements is illustrated by this example? d) Give another example of a set of elements which are classified according to this law. a) The average atomic mass of X and Z =
7 + 39 46 = = 23 2 2
b) The average atomic mass of X and Z is equal to the atomic mass of Y c) The law illustrated in this example is Dobereiner’s law of triads. d) Another example of Dobereiner’s law is Calcium, Strontium and Barium. 11.
What are the limitations of Dobereiner’s law of triads? Dobereiner’s classification was not satisfactory, as he failed to arrange all of the then known elements in the form of triads. He could identify only three triads from the elements known at that time.
12.
State Newland’s law of Octaves. New land law of octaves states that “When elements are arranged in the order of increasing atomic mass, the properties of the eighth element (starting from any given element) are a repetition of the properties of the first element”.
13.
What similarity was observed by Newland in the properties of elements and octaves of music? When Newland arranged the elements, he found that the properties of eighth element resembled the properties of the first element, This repetition in the properties is just like the repetition of eighth note in an octave of music. (sarega ma pa da nisa)
14.
X and Y are the two elements having similar properties which obey Newland’s law of octaves. How many elements are there in-between X and Y? There are 6 elements between X and Y
15.
Why Newland law of octaves is called so? As Newland law is similar to the octaves in music, he called the law as law of octaves.
16.
What are the limitations of Newland law of Octaves? Newland law of octaves could not be extended after 17 elements.
17.
State Mendeleev’s periodic law. Mendeleev’s periodic law states that “The properties of elements are periodic functions of their atomic mass”.
18.
What was the Mendeleev’s basis for classification of elements? Mendeleev’s classification is based on atomic mass.
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C3: Periodic Classification of elements
21
Mention the merits of Mendeleev’s periodic law. Mendeleev left vacant spaces in the table for the elements that were to be discovered. He was able to predict the atomic mass and properties of elements even before their discovery. His periodic table helped to discover new elements like germanium.
20.
State the characteristics of Mendeleev’s periodic table. 1) Mendeleev’s periodic table consists of 7 periods (horizontal) and 9 groups (vertical). 2) Elements are arranged in the increasing order of their atomic weights. 3) The elements that have similar property were placed in vertical columns.
21.
Atomic mass is not useful to construct the periodic table. Give reasons with an example. OR Why is atomic number is more useful than atomic mass to classify the elements? Isotopes of an element have same atomic number but different atomic mass. They have to be placed in four places. This creates confusion because other elements occupied these positions.
22.
What is meant by isotope of an element? The meaning of isotope is iso-same, tope-place. Atoms having different atomic masses with the same atomic number. They are given the same place in the periodic table.
23.
State Modern periodic law. Modern periodic law states that “The properties of elements are a periodic function of their atomic number”.
24.
Mention the characteristics of modern periodic table. When elements are arranged according to increasing atomic numbers, elements having similar properties are kept in the same group. There is a inter relation between electronic configuration and atomic number. The elements are arranged in 7 horizontal rows called periods and 18 vertical columns called groups.
25.
What is the significance of atomic number in the modern classification of elements? In the modern classification, elements are arranged in the increasing order of their atomic numbers.
26.
What are periods and groups in the modern periodic table? The horizontal rows in the periodic table are called periods. The vertical columns in the periodic table are called groups.
27.
How many periods and groups are there in the modern periodic table? In the modern periodic table there are 7 periods and 18 groups.
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C3: Periodic Classification of elements
Compare the arrangement of elements in Mendeleev’s and Modern periodic table. Mendeleev’s periodic table
29.
22
Modern periodic table
1. Elements are arranged in the order of increasing atomic masses.
1. Elements are arranged in the order of increasing atomic numbers.
2. There are 8 groups
2. There are 18 groups
Consider the isotopes of carbon, C-12 and C-14. Would you place them in different slots because their atomic masses are different or would you place them in the same position because their chemical properties are the same? Isotopes are not placed according to their atomic mass but they are all placed in the same position as they have the same atomic number.
30.
Consider the following isotopes
35
17 Cl
and
37
17 Cl
. Explain why.
a) they have identical chemical properties. b) they are placed in the same position in the modern periodic table, a) They have same atomic number b) All isotopes are placed in the same position in the modern periodic table. 31.
Give reason: Elements of group 18 are called zero group elements. Elements of group 18 have valency of zero. Hence they are called zero group elements.
32.
Give reason: Elements of group 18 or group zero are called inert or noble gases. Elements of group 18 do not form chemical bond on their own with other elements as they have completed shells of electrons. They have no tendency to gain or lose electrons. Hence they are most un-reactive.
33.
Why do inert gases have zero valency?
34.
Inert gases have zero valency because their octet is complete. Why are noble gases chemically unreactive?
35.
Noble gases do not form chemical bond on their own with other elements as they have completed shells of electrons. Why are noble gases placed in a separate group?
36.
Nobel gases are very unreactive. So, they are placed in a separate group. Give example of noble gases or inert elements.
37.
Helium, Neon, Argon, Xenon, Krypton etc. What is octet structure?
38.
The electronic structure of elements having 8 electrons in the outermost shellis called octet structure. Is it possible to have an element having atomic number 1.5?
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23
Atomic number is always a whole number. It can either be 1 or 2. There can be no element with atomic number 1.5
39.
List the short period, long period and incomplete periods in the modern periodic table. Periodnumber 1st
Number of elements
Veryshort
2 (H & He)
nd
2
Short
8 elements (Li to Ne)
3rd
Short
8 elements ( Na to Ar)
th
Long
18 elements (K to Kr)
th
Long
18 elements (Rb to Xe)
th
6
Very long
32 elements (Cs to Rn)
7th
incomplete
Rest of the elements (Fr onwards)
4 5
40.
Description
What are Lanthanides and Actinides? The 14 elements coming after Lanthanum are called Lanthanides. 14 elements coming after actinium are called Actinides.
41.
Why are Lanthanides and Actinides placed separately? OR Give reason: ‘f’ block elements are kept separately in the periodic table. Lanthanides and Actinides are series of elements having similar properties and they are placed at the bottom of the periodic table so that the periodic table can fit on a single page for our convenience. They is more horizontal similarity rather than vertical similarity.
42.
How does the electronic configuration of an atom relate to its position in the modern periodic table? The group number of elements having up to two valence electrons is equal to the number of valence electrons. For example:
Group 1 elements have 1 valence electron. Group 2 elements have 2 valence electrons. Group 13 elements have 3 valence electrons.
43.
How is the electronic configuration of an atom related to the period in the periodic table? Periods are formed according to the way in which electrons get filled up in different shells and orbitals. For example first period of the table is completed when the first shell of the atom is completely filled up.
44.
Give reason: In the first period, hydrogen and helium are not placed adjacent to each other OR There is a big gap between hydrogen and helium in the periodic table. Because Hydrogen and Helium belong to different groups. The Hydrogen element belongs to the 'Hydrogen' group, whereas the Helium element belongs to the 'noble gas'
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C3: Periodic Classification of elements
group. Helium should be next to hydrogen. But the 2nd group of elements are alkaline earth metals and Helium is a Noble gas, therefore it is decided that Helium be grouped with all the Noble gases.
45.
What are transition elements? Elements where electrons of their atoms occupy ultimate shells leaving penultimate (last but one)shells partially vacant are called transition elements. Electrons of these elements fill normally upto 1s, 2s, 2p, 3s and 3p. After 3p electrons occupy 4s leaving 3d orbitals vacant.
46.
Why are‘d block’ elements called outer transition elements? ‘d block’ elements are called outer transition elements because they contain at most two electrons in their outer shell.
47.
Why ‘f block’ elements are called inner transition elements? The elements for which f sub shells are filling are called the inner transition elements.
48.
How elements are classified based on electronic configuration? Based on electronic configuration, all elements are grouped into four categories. They are ‘s block’, ‘p block’, ‘d block’ and ‘f block’ elements.
49.
How is the block to which an element belongs determined? If we know the atomic number and electronic configuration of an element, we can find the block to which they belong. If the outermost sub energy level is ‘s’ then it belongs to ‘s block’. If the outermost sub energy level is ‘p’ then it belongs to ‘p block’. Example: Atomic number of sodium is 11. Its electronic configuration is 1s2, 2s2, 2p6, 3s1. The orbital occupied by the outermost electron is s. So sodium belongs to‘s’ block.
50.
Find the block to which the following elements belong. a) Aluminium (Atomic number: 13) 2
2
6
2
Electronic configuration of aluminium is 1s , 2s 2p ,3s 3p
1
The orbital occupied by the ultimate electron is ‘p’. So aluminium belongs to ‘p’ block. b) Iron (Atomic number 26) 2
2
6
2
10
2
Electronic configuration of Iron is 1s , 2s 2p , 3s 3d , 4s
The orbital occupied by the penultimate shell is‘d’. So iron belongs to ‘d’ block. c) Cerium (Atomic number 58) 2
2
6
2
6
10
2
6
10
2
2
6
Electronic configuration of Cerium is 1s , 2s 2p , 3s 3p 3d ,4s 4p 4d 4f , 5s 5p , 2 6s The orbital occupied by the penultimate shell is ‘f’. So Cerium belongs to ‘f’ block. 51.
How is the period to which an element belongs determined?
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C3: Periodic Classification of elements
If we know the atomic number and electronic configuration of an element, we can find the period to which it belongs by finding the number of shells. Total number of shells indicates period number. 2
2
6
2
Example: Atomic number of Calcium is 20. Its electronic configuration 1s , 2s 2p , 3s 6 2 3p , 4s . Highest shell number is 4 so calcium belongs to the 4th period.
52.
To which period do the following elements belong? a) Manganese (Atomic number:25) Atomic number of Manganese is 25 2
2
6
2
6
5
2
Its electronic configuration is 1s , 2s 2p , 3s 3p 3d , 4s Highest shell number is 4 so it belongs to 4th period. b) Zinc (Atomic number: 30) Atomic number of zinc is 30.
53.
Its electronic configuration is 1s2, 2s2 2p6, 3s2 3p6 3d10, 4s2 Highest shell number is 4, so it belongs to 4th period. What is meant by the term periodicity?
54.
When the elements are arranged in order of increasing atomic numbers, elements with similar chemical properties are repeated at definite intervals. This is known as periodicity. The cause of periodicity is the recurrence of similar electronic configuration. What are the factors that decide the chemical behaviour of elements? a) Periodicity of chemical properties b) Atomic size c) Ionisation energy d) Electro chemical nature e) Metallic nature
55.
What is atomic size? How does it affect the chemical properties of an element? The distance between the centre of the nucleus and the outermost electron shell of an atom is called atomic size. It refers to the radius of the atom. Size of an atom decides ionization energy and electron affinity. Electron affinity decides electro-negativity and electro-positivity.
56.
What happens to the atomic size as we move a) Horizontally from left to right in a period of the periodic table? b) Down the group of the periodic table? a) Atomic size decreases as we move from left to right along a period. b) Atomic size increases as we go down a group.
57.
Why does atomic size (radius) decrease across a period? The atomic radius decreases along a period because the atomic number increases by one, but the additional electron goes to the same shell.There is no change in the number of shells but more electrons make the nucleus to exert greater inward pull on the electrons. As a result, outer electrons are pulled in closer to the nucleus which leads to contraction of the atom and thus decrease in atomic size.
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Decreases
Atomic size (radius) → Across a period (left to right) Ex: Atomic size of Lithium (Li)>Beryllium (Be) > Boron (B) > Carbon (C) > Nitrogen (N) > Oxygen (O) > Fluorine (F) 58.
Give reason: Atomic size of sodium atom is greater than that of chlorine atom. Sodium is in the 1st group where as chlorine is in 17th group. We know that the atomic size decreases down the group. Hence sodium atom has larger atomic size than that of chlorine atom.
59.
Why does atomic size of an atom increase down the group? In moving down a group, new shell is added to the atom. There is an increase in the energy level. The distance of the outermost electron from the nucleus increases. This increases the size of the atom down the group.
60.
Arrange the following elements in increasing order of their atomic size. a) Li, Be, F, N
b) Cl, At, Br, I
a) F
What is meant by ionisation energy? Ionisation energy is the energy required to remove the electron from the outermost shell from a free and isolated atom of the element.
62.
How does ionisation energy vary across a period and down a group? Ionisation energy increases along a period and decreases down a group. Ionisation energy decreases with increase in the atomic size. Increases
Ionisation energy → Across a period (Left to right)
63.
Give reason: Sodium atom has lower ionisation energy than chlorine atom. Sodium is in the 1st group whereas chlorine is in 17th group. Atomic size decreases down the group. We know that Ionisation energy increases with decrease in atomic size. Hence sodium atom has lower ionisation energy than that of chlorine atom.
64.
What is meant by electro-positive? Atoms which give up electrons easily are called electro-positive. Ex: Sodium atom.
65.
What is meant by electro negative? Atoms which accept electrons easily are called electro negative. Ex; Chlorine.
66.
How does electro positivity and electro negativity vary across a period and down a group?
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Electro positivity decreases along a period and increases down the group. Electro negativity increases a period and decreases down the group. Decreases
Electro positivity → Across a period (Left to right) Increases
Electro negativity → Across a period (Left to right)
67.
A group of elements in the periodic table are given – Boron, Aluminium, Gallium, Indium, Thallium [Boron is the first member of the group and Thallium is the last] Which element would have the highest electro negativity? Boron would have the highest electro negativity as it decreases down the group.
68.
Nitrogen (atomic number 7) and Phosphorous (atomic number 15) belong to group 15 of the periodic table. Which of these will be more electro negative? Why? Nitrogen will be more electro negative as it decreases down the group.
69.
In period 2, element ‘A’ is to the right of element ‘B’. a) The element ‘A’ would have a _______ atomic size than ‘B’. b) The element ‘B’ would have a _______ ionisation potential then ‘A’. a) Lower b) Lower
70.
Arrange the following elements as given in the brackets: a) Na, Cl, Mg, P [in decreasing order of atomic size] b) Cl, Al, Na, S [ in increasing order of ionisation energy] c) Ar, He, Ne [in increasing order of number of electronic shells] a) Cl, P, Mg, Na
71.
Give reason: sodium has lower electron affinity than chlorine atom. As electron affinity increases across a period (from left to right)
72.
How does metallic nature vary along a period and down a group? Metallic nature decreases along a period and increases down the group. Example: In the 14th group there are elements carbon, silicon, germanium, tin and lead. Carbon and silicon are non-metals, tin and leads are metals.
73.
In which part of the periodic table do we find mostly metals and non-metals? Most metals are found on the extreme left side of a period. Most non-metals are found on the right side of a period.
74.
Which of the following elements have maximum metallic characteristics? Ga, Ge, As, Se, Be
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Maximum metallic character is found in elements on the extreme left side of the periodic table. Out of the given elements Beryllium will have maximum metallic character as it is on the extreme left side in the periodic table. 75.
What are metalloids? Give example. Elements which are not distinctively metals and possess some physical properties of nonmetals are called metalloids.
76.
77.
What is the name of those elements which divide metals and non-metals in the periodic table? Metalloids List the elements of 15th group of the periodic table. Name the distinct metals and non-metals of the group. The elements of 15th group are Nitrogen, Phosphorous, Arsenic, Antimony and Bismuth. Nitrogen and phosphorous are non-metals. Arsenic and Antimony are metalloids, Bismuth is a metal.
78.
Taking first period and 17th group of the periodic table, write gradation of properties with respect to the following: a) atomic size b) Ionisation energy c) electro positivity and electro negativity. The elements of 1st period are hydrogen and helium. a) Atomic size of hydrogen is larger then that of helium because atomic size decreases across a period. b) Ionisation energy of helium is larger than that of hydrogenbecause ionisation increases across a period. c) Electro positivity of hydrogen is higher than that of helium because it decreases across the period. Electro negativity of helium is higher than that of hydrogen becauses it increases across the period. The elements of 17th group are Fluorine, Chlorine, Bromine, Iodine and Astatine. a) Atomic size of Astatine is larger because it increases down the group. b) Ionisation energy of Fluorine is higher because it decreases down the group. c) Electro positivity of Astatine is higher as it increases down the group. Electro negativity of fluorine as it decreases down the group.
79.
Mention the advantages of the periodic table. a) Study of chemistry is simplified and organized leading to easy access of data of the elements. b) It was possible to predict the atomic mass, some properties and other details of elements which are yet to be discovered during the time of Mendeleev. c) There is striking similarity between the periodic table constructed empirically by Mendeleev and the modern periodic table based on electronic configuration and nature of chemical bond. d) Interpretation of trends and periodicities of properties of elements provide a clear understanding and proof for atomic behavior. e) It is possible to predict the properties of elements by considering the position of elements in the periodic table. On the other hand properties of element helps us to predict the position of an element in the periodic table.
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C3: Periodic Classification of elements
29
The following shows a part of the periodic table containing first three periods in which five elements have been represented by the letters a, b, c, d and e. a) Select the letter which represents a metal. b) Select the letter which represents a noble gas. a) d b) c
81.
The position of three elements A, B and C in the periodic table shown below: a) State whether A is a metal or non-metal. b) State whether C is more reactive or less reactive than A. c) Will C be larger or smaller in size than B?
Group 16 Group 17 -
-
-
A
a) Metals lie on the left side where as non-metals are B C placed on the right side of the periodic table. Group 17 is on the right side of the periodic table, thus element A is non-metal. b) The chemical reactivity of non-metals decrease down the group, so element C is less reactive than A c) The atomic size decreases moving from left to right along a period. So atom C will be smaller in size than B. 82.
What are the periodic trends in a period? a) The number of valence electrons increases from left to right. b) The atomic size decreases. c) The non-metallic character increases. d) The ionisation energy increases.
Moving Left → Right • Atomic Radius Decreases • Ionization Energy Increases • Electro negativity Increases Moving Top → Bottom • Atomic Radius Increases • Ionization Energy Decreases • Electro negativity Decreases
83.
Give reason: In the construction of periodic table, the periodic law is broken in some places. Hydrogen resembles both the alkali metals and halogens. But it has been placed with the alkalis. The lanthanides and actinides have not been placed in the main body of the table.
1.
The person in 1815 who suggested in that elements can be classified on the basis of atomic mass was William Prout.
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2.
First attempt of classification of elements was made by Dobereiner.
3.
The German chemist who pointed out that many of the known elements could be arranged in groups of three similar elements was Dobereiner.
4.
Elements arranged in group of three are called triads.
5. 6.
The periodicity of repetition of properties in Newland’s law was eight. The contribution of Newland in the classification of element is the word periodic.
7.
According to Newland’s classification of elements, the properties of sulphur are similar to those of oxygen because sulphur is the eighth element starting from oxygen.
8.
Mendeleev arranged the elements in his periodic table on the basis of atomic mass.
9.
The Russian chemist who said that the properties of elements are periodic function of their atomic mass is Dmitri Mendeleev.
10.
The modern periodic table was adopted by IUPAC in 1984.
11. 12.
The full form of IUPAC is International Union of Pure and Applied Chemistry. The horizontal rows of periodic table are called periods.
13. 14.
The cause of periodicity is the recurrence of similar electronic configuration. The vertical columns of periodic table are called groups.
15. 16.
There are 18 groups and 7 periods in the modern periodic table. The group eighteen elements are called zero group or inert or noble gas.
17.
The group which has completely filled valence shell is eighteen.
18. 19.
Elements with eight electrons in their outermost shell are called noble gases. The element which is the most reactive of all elements in the periodic table is fluorine.
20. 21.
The element which is referred to as “the element that consumes everything” is fluorine. In the modern periodic table, the elements are arranged in the ascending order of their atomic number.
22. 23.
The shortest period in the periodic table is first period. The longest period in the periodic table is sixth period.
24. 25.
The incomplete period in the periodic table is seventh period. The group number of the element neon is 18.
26.
The period number of the element aluminium is 3.
27.
Horizontal similarity can be observed in the period number 6 & 7.
28.
The similarity in the properties of a group of elements is because they have same number of outer electrons.
29.
The distance between the centre of the nucleus and the outermost electron shell of an atom is called atomic size.
30.
The atomic size decreases as we move from left to right across the period.
31.
The elements below sodium in the same group would have lower electro negativity.
32.
The elements above chlorine would have higher ionisation energy.
33.
The element from the elements Li, Na, K, having the least number of electron shells is Li.
34.
The element with the least atomic size from Carbon, Nitrogen, Boron and Beryllium is Nitrogen.
35.
The element with highest ionisation energy from the elements of period 1, 2, 3 is period 1.
36.
The first element of 14th group is carbon, which is a non-metal. The metallic members of this group are tin and lead.
37.
On going down in a group in the periodic table, the metallic nature of element increases.
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38.
Elements which are not distinctively metals and possess some physical properties of nonmetals are called metalloids.
39.
Atoms which give up electrons easily are called electro-positive.
40.
Atoms which receive electrons easily are called electro negative.
41.
The energy required to remove the electron from the outermost shell from a free and isolated atom of the element is called Ionisation energy.
42.
Elements in which electrons of their atoms occupy ultimate shells leaving penultimate shells partially vacant are called transition elements.
****
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Chapter 4: Silicon 1.
C4
Write a note on occurrence of silicon. Silicon is the 2nd most abundant element in the earth’s crust. It is widely distributed in sand, various forms of silicon dioxide (silica) or silicates. It is the chief constituent of semiprecious stones like garnet, zircon, topaz and opal.
2. Write the electronic configuration of silicon The atomic number of silicon is 14 and its mass number is 28. Its electronic configuration 2 2 6 2 2 is 1s , 2s 2p , 3s 3p 3.
Name the two allotropic forms of silicon. a) Amorphous silicon b) Crystalline silicon
4.
Briefly explain the extraction of amorphous silicon. Finely powdered silica (sand or quartz) is mixed with magnesium powder and heated in a fire clay crucible. Magnesium oxide and silicon are formed. Heat SiO2 + 2Mg → Si + 2MgO
The product is washed with dilute hydrochloric acid to dissolve magnesium oxide. Then it is washed with hydrofluoric acid to remove unreacted silica. The powder left behind is amorphous silicon. 5.
What is the role of the following in the extraction of amorphous silicon? a) Hydrochloric acid b) hydrofluoric acid a) Hydrochloric acid is used to dissolve magnesium oxide b) Hydrofluoric acid is used to remove unreacted silica.
6.
How is crystalline silicon prepared? Crystalline silicon is prepared by reducing silica with coke. When excess of silica is heated with coke in an electric furnace in the absence of air, dark grey coloured silicon in its crystalline form is obtained. Heat SiO 2 + 2C → Si + 2CO
7.
Compare the properties of amorphous and crystalline silicon
Amorphous silicon
8.
Crystalline silicon
It is a brown powder
It is a dark grey crystalline solid and rough. It resembles the structure of diamond
It does not conduct electricity at low temperatures.
Slightly conducts electricity
It is more reactive than crystalline silicon
It is less reactive than amorphous silicon
When heated in air, it oxidizes at the surface level & catches fire
It does not burn in air even when heated
What happens when amorphous silicon is heated? When amorphous silicon is heated in air, it oxidizes at the surface level & catches fire.
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What happens when silicon is burnt in air? Silicon burns brilliantly in air and vigorously in oxygen to form silicon dioxide. It is an exothermic reaction. Si + O 2 → SiO 2
10.
What is an exothermic reaction? A chemical reaction in which heat is liberated is called exothermic reaction. Ex: Dissolution of sodium hydroxide, calcium oxide, sulphuric acid and combustion of fuel.
11.
How does red hot silicon react with steam? Silicon is insoluble in water. It slowly decomposes with steam. When silicon is in red hot state, it reacts with steam liberating hydrogen. Si + 2H 2 O → SiO 2 + H 2 (Steam)
12.
Give reason: Even though silicon is a non-metal it resembles metals in its properties. When red hot silicon reacts with steam, it liberates hydrogen. Even when metals like hot iron, zinc or magnesium react with steam, they liberate hydrogen with their respective metal oxides. Hence silicon resembles metals in some properties.
13.
How is silicon carbide formed? OR What happens when silicon and coke are heated? When a mixture of silicon and coke is heated in an electric furnace, silicon carbide is formed. It is an endothermic reaction. Si + C → SiC
14.
What is an endothermic reaction? A chemical reaction in which there is absorption of heat is called endothermic reaction. Ex: Dissolution of ammonium chloride, common salt and sugar in water, cooking of rice
15.
What is carborundum? How is it prepared? Carborundum is chemically silicon carbide. When a mixture of silicon and coke is heated in an electric furnace, silicon carbide is formed. Si + C → SiC
16.
Mention some uses of silicon compounds. a) Quartz is used in modern clocks. b) Zircon, topaz are used to make ornamental objects. c) Sand is used in buildings to make concrete mix. d) Sand is used in preparation of glass. e) Silicon carbide is used in cutting and grinding tools, polishing. f) Zeolite is used in removal of hardness of water and in chromatography. g) Silicon is used as raw material in the production of silicones.
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h) Silicones are used in water proofing treatments, moulding compounds, insulating material for electric motors and other electrical appliances. i) j)
Silica gel is used in chromatography. It is used in manufacture of transistor, diodes and integrated circuits (IC).
k) Silica is used in manufacture of emery paper or sand paper. l) 17.
It is used as sand bath during roasting and in laboratory to carry out chemical reaction.
What are silicones? Silicones are rubbery compounds of silicon, oxygen and hydrocarbons.
18.
Give reason: Silicones used as insulating materials. Unlike common organic polymers, silicones do not catch fire. Hence they are used in fire proof suits and insulating material.
19.
Give reason: Silicon is used widely even through Germanium is a better semiconductor material. Silicon is the second most abundantly available material and it can be used at higher temperature. Hence it widely used than Germanium.
20.
Give reason: Carbon is not a semiconductor inspite of it’s group being 14. Conductivity increases as you go down a group, so carbon, at the top of its group, is usually described as a resistor and silicon and germanium are described as semiconductors. Continuing down the group, tin and lead are conductors.
21.
Give reason: Sand is used during roasting and as sand bath in chemical reactions. As silicon has high thermal and non combustible property.
22.
Give reason: Silicon compounds have water repelling property. Due to the absence of porosity in the polymer of silicon. The structure is so compact that water cannot enter.
23.
Mention the biological significance of silicon. a) Diatoms, radiolarian and siliceous sponges use biogenic silica as a structural material to construct skeletons. b) Paddy needs silicon for its growth.
24.
What are the hazards of silicon? Miners and stone breakers, in asbestos factory, glass factory some times suffer from a professional hazard.
25.
26.
What is silicosis? How is it caused? Silicosis a professional disease which affects miners and stone breakers. Silica particles suspended in air in the mining area enters into lungs of workers and causes silicosis. Give reason: Workers in mines, glass factory, asbestos factory and stone breakers often suffer from silicosis.
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Silica particles suspended in air in the mining area enters into lungs of workers and causes silicosis. Give reason: Workers in mines, glass factory and asbestos factory must be provided with gas masks. Because long exposure to silica particles suspended in air enter lungs of workers and causes silicosis.
Fill in the blanks: 1.
The chemist who produced crude silicon from silicon dioxide was Berzelius.
2.
The chemist who proved that sans is a compound and not an element was Berzelius.
3. 4.
Silicon is derived from the Latin word Silicium which means stone or flint. The atomic number of silicon is 14 and its mass number is 28.
5.
The electronic configuration of silicon is 1s , 2s 2p , 3s 3p .
6.
The two allotropic forms of silicon are amorphous and crystalline.
7. 8.
Amorphous silicon is obtained by heating silica with magnesium powder. During preparation of amorphous silicon, product is washed with dilute hydrochloric acid to dissolve magnesium oxide.
9. 10.
During preparation of amorphous silicon, the product is washed with hydrofluoric acid to remove unreacted silica. Crystalline silicon is obtained by reducing silica with coke.
11. 12. 13.
A chemical reaction in which heat is liberated is called exothermic reaction. The gas liberated when red hot silicon reacts with steam is hydrogen. A chemical reaction in which there is absorption of heat is called endothermic reaction.
14. 15.
Carborundum is chemically silicon carbide. Carborundum is prepared heating a mixture of silicon and coke in an electric furnace.
16.
The compound of silicon used in modern clocks is quartz.
17. 18.
The compound of silicon used in making ornaments is Zircon / Topaz. The compound of silicon used in building construction is sand.
19.
The compound of silicon used in cutting & grinding tools is silicon carbide/carborundum.
20. 21. 22.
The compound of silicon used in preparation of glass is sand. The compound of silicon used in removing hardness of water is Zeolite. The compound of silicon used in water proof treatment is silicone.
23.
The compound of silicon used as insulating material for electric motors/appliances is silicone.
24.
Silicon is a semiconductor.
25. 26.
The rubbery compound of silicon, oxygen and hydrocarbons is called silicone. The compound of silicon used in chromatography is silica gel.
27.
The element of used in making integrated circuits is silicon.
28. 29.
The element used in manufacture of transistor, diodes and integrated circuits is silicon. The compound used in manufacture of emery paper or sand paper is silica.
30.
An example of an organism which uses biogenic silica as a structural material to construct skeletons is Diatoms, radiolarian and siliceous sponges.
31.
A professional disease formed which affects miners and stone breakers is silicosis.
2
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Chapter 5: Green Plants and Chordates 1.
B5
How is kingdom Metaphyta (plantae) classified? Kingdom plantae is divided into: a) Non-vascular plants b) Vascular plants
2. What does Kingdom Metaphyta include? Kingdom Metaphyta includes a) Multicellular algae – red algae, brown algae, green algae b) Bryophytes 3.
What do vascular plants include? Vascular plants include: a) Pteridophytes
4.
b) Gymnosperms
c) Angiosperms
What are non-vascular plants? The group of plants in which xylem and phloem are absent are called non-vascular plants.
5.
What are vascular plants? The group of plants in which xylem and phloem is present are called vascular plants.
6.
Mention the characteristics of multi-cellular algae. a) Algae are autotrophic organisms. b) They have green pigment chlorophyll. c) They are major producers in marine ecosystem. d) They are non-vascular plants. e) They have a plant body called thallus. f) They are eukaryotic with prominent nucleus and many plastids. g) The cell wall is composed of cellulose and pectin. h) Algae reproduce by vegetative, asexual and sexual methods. Vegetative reproduction is by fragmentation of thallus. Asexual reproduction takes place by formation of spores. Sexual reproduction is by fusion of male and female gametes. Example: Spirogyra, Ulothrix, Batrachospermum, Polysiphonia, Sargassum and Ectocarpus.
7.
What is thallus? The flat plant body of algae is called thallus.
8.
Mention the pigments present in the following algae. a) Green algae b) Red algae c) Brown algae a) Green algae – green pigment chlorophyll b) Red algae – green pigment chlorophyll, red pigment phycoerythrin. c) Brown algae – green pigment chlorophyll, brown pigment xanthophyll.
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How do Multicellular algae reproduce? Multicellular algae reproduce by vegetative, asexual and sexual methods. Vegetative reproduction is by fragmentation of thallus in which the thallus breaks into small fragments which grow into new plant. Asexual reproduction takes place by formation of spores. Sexual reproduction is by fusion of male and female gametes.
10.
Mention the economic importance of multicellular algae. a) Some species of algae are used as cattle feed. b) Algin, a substance obtained from brown algae is used in preparation of ice creams and chocolates. c) Agar, a substance obtained from Gelidium a red algae is used as a medium for culturing bacteria in the laboratory. d) Red algae called Porphyra is used as a condiment. e) Algae growing in decaying water liberate oxygen and help in purification of water. f) Laminaria, a brown algae is used in the production of potassium and iodine.
11.
Mention the characteristics of bryophytes. a) Bryophytes are autotrophic organisms. b) They are called amphibians of plant kingdom. c) They have green pigment chlorophyll. d) They have a plant body called thallus. e) They have small unicellular root like extensions called rhizoids. f) They include two groups – liverworts and mosses. g) Their life cycle includes two generations – gametophytes and sporophytes. h) They reproduce sexually. Ex: Riccia, Marchantia, polytrichum, funaria.
12.
Give reason: Bryophytes are referred to as amphibians of plant kingdom. Bryophytes are plants that are found both on moist land and in water. They need water for completing the life cycle. Hence they are referred to as amphibians of plant kingdom.
13.
What are rhizoids? Rhizoids are the root like extensions present in bryophytes.
14.
Name the two groups of bryophytes and give one example for each group. Bryophytes are divided into two groups: a) Liverworts Ex: Riccia, Marchantia
15.
b) Mosses Ex: Polytrichum, funaria Give reason: Liverworts are called so. Liverworts like Riccia are called so because they resemble the shape of liver.
16.
Name the two generations in the life cycle of bryophytes. The life cycle of bryophytes include two generations Gametophyte and Sporophyte.
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What is gametophyte? The adult plant body of a bryophyte which produces male and female gametes is called gametophyte.
18.
What are antheridia and archegonia? Antheridia are the male gamete producing structures in bryophytes/pteridophytes Archegonia are the female gamete producing structures in bryophytes/pteridophytes.
19.
What are sporophytes? The sporophytes are diploid spore producing structures.
20.
Mention the differences between gametophyte and sporophyte. Gametophyte 1. It is gamete producing structure 2. It is haploid 3. It is capable of photosynthesis & can lead independent life
21.
Sporophyte 1. It is spore producing structure 2. It is diploid 3. It depends on gametophyte
What is meant by alternation of generations in bryophytes? Explain The process by which gametophyte and sporophyte formed alternately during the life cycle is called alternation of generations. The life cycle of bryophyte includes two successive generations namely a haploid gametophyte and a diploid sporophyte. The adult gametophyte produces male and female gametes. The fusion of male and female gametes produces zygote which develops into a diploid sporophyte. The spores on germination produce gametophyte.
22.
What are bog mosses? Where do they grow in Karnataka? Mosses growing in marshy places are called bog mosses. They are abundant in districts of Madikeri, Chikkamagalur, Hassan and shivamogga.
23.
A plant growing on moist soil has a thalloid body, rhizoids and archegonium. To which group of Metaphyta do you include it? Give one example of the group. The plant belongs to bryophyte Ex: Riccia, Funaria etc.
24.
Write the economic importance of bryophytes. a) Mosses are used in packing flowers. b) They are used in pots for moisture retention. c) They check erosion as they form a dense mat on the soil.
25.
d) They decompose the rocks and contribute to soil formation. What are Pteridophytes? Pteridophytes are vascular plants. They are the first terrestrial plants to develop vascular tissues.
26.
What are tracheophytes?
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Tracheophytes are the group of plants containing vascular tissues. 27.
Give reason: Pteridophytes are included under tracheophytes. As pteridophytes have vascular tissues, they are included under tracheophytes.
28.
Mention the characteristics of pteridophytes. a) Pteridophytes are vascular plants. b) They were the first terrestrial plants to develop vascular tissues. c) They grow in moist soil, on damp walls, cool & shady regions. The plant body can be divided into root, stem and leaves. d) They are commonly called ferns. e) The life cycle includes two generations namely gametophyte and sporophyte. f) The adult plant body is called sporophyte. g) They reproduce by asexual and sexual methods. Asexual reproduction is by spore formation. Sexual reproduction is by fusion of male and female gametes. Ex: Nephrolepis, Selaginella, Adiantum, Lycopodium, Marsilea.
29.
What is sporophyte of pteridophytes? Sporophyte is the adult plant body in pteridophytes.
30.
How do pteridophytes reproduce asexually? Pteridophytes reproduce asexually by producing haploid spores. The spores germinate into a haploid gametophyte.
31.
What is Prothallus? Prothallus is an independent structure developed in pteridophytes which produces male and female gametes,
32.
How do pteridophytes reproduce sexually? Prothallus an independent structure produces male and female gametes called antheridia and archegonia. The gametes fuse and forms zygote developing into a sporophyte.
33.
Explain alternation of generations in pteridophytes. The process by which gametophyte and sporophyte formed alternately during the life cycle is called alternation of generations. The life cycle of pteridophytes includes two successive generations namely a haploid gametophyte and a diploid sporophyte. The sporophyte produces spores which germinate into haploid gametophyte called Prothallus. Fusion of male and female gametes results in zygote which develops into a sporophyte.
34.
Mention the differences between bryophyte and pteridophyte. Bryophyte 1. It is a non-vascular plant 2. The adult plant body is a haploid gametophyte.
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Pteridophyte 1. It is a vascular plant 2. The adult plant body is diploid sporophyte.
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Why is Adiantum referred to as walking fern? When the leaves of Adiantum touch the ground, they develop roots and form a new plant. Hence it is called walking fern.
36.
Mention the economic importance of pteridophytes/ferns. a) Ferns are grown for their ornamental value. b) Leaves of pteridophytes are used in making flower bouquet. c) Some ferns are of medicinal importance. d) Some ferns like horse-tail and club mosses are involved in the formation of fossil fuels like coal and petroleum.
37.
What is the significant characteristic acquired by pteridophytes in the process of evolution? Give 2 examples of pteridophytes. The significant characteristic acquired by pteridophytes is vascular tissues (xylem and phloem). Ex: Nephrolepis, Selaginella, Adiantum, Lycopodium, Marsilea
38.
What are gymnosperms? Gymnosperms are naked seed bearing vascular plants. (Gymnos=naked, sperma=seeds)
39.
Why are gymnosperms referred to as naked seeded plants? Gymnosperms produce seeds which are exposed and not enclosed in fruits. Hence they are commonly called naked seeded plants.
40.
Mention the characteristics of gymnosperms. a) Gymnosperms are naked seed bearing vascular plants. b) They grow on mountain tops at low temperature. c) They mostly comprise of ever green trees. d) The plant body is a sporophyte. e) They produce prominent structures called cones. f) They reproduce by fusion of male and female gametes resulting in formation of zygote. It becomes the seed. Ex: Cycas, pinus, araucaria, cupresscus.
41.
Write a brief note on cones in gymnosperms The sporophyte of gymnosperms produce prominent structures called cones. They produce two types of cones – male cone and female cone. Male cones contain numerous microsporophylls which produce microspores that have male gametes. Female cones contain megasporophylls which produce ovule containing female gametes.
42.
What are microsporophyll and megasporophyll? Microsporophylls are the numerous structures in the male cone of gymnosperms that produce the male gametes. Megasporophylls are the structures in the female cone of gymnosperms that produce ovule containing female gametes.
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Distinguish between microsporophyll and megasporophyll. Microsporophyll They are structures that produce the male gametes called microspores
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B5: Green plants & Chordates
Megasporophyll They are structures that produce female structures called megaspores.
What are angiosperms? Angiosperms are a group of plants in which the seeds are enclosed in structures called fruit. (Angion=cover, sperma=seed)They are the most evolved group of plants.
45.
Mention the characteristics of angiosperms. a) Angiosperms are group of plants in which seeds are enclosed in structure called fruit. b) They are the most evolved group of plants. c) The adult plant body is sporophyte. d) Flowers are the reproductive part of the plant. e) Flowers may be found singly or in a cluster. f) They are of two types monocots and dicots.
46.
What is meant by inflorescence? A special branch containing a cluster of flowers is called inflorescence.
47.
Draw a neat diagram showing the structure of a typical flower and label the parts.
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Write the male parts of a flower. Anther and filament are the male parts of a flower.
49.
Write the female parts of a flower
50.
Stigma, style and ovary are the female parts of a flower. Distinguish between monocot and dicot seed. Monocot seed
51.
1. Monocot seeds contain only one 1. Dicot seeds contain two cotyledons. cotyledon. 2. During germination, the cotyledons 2. During germination, the cotyledons remain below the soil. appear above the soil Distinguish between root system of monocot and dicot. Monocot root system 1. They have fibrous root system 2. The primary root is short lived 3. Roots develop from the base of the stem.
52.
Dicot seed
Dicot root system 1. They have tap root system 2. The primary root continues to grow throughout the life of the plant. 3. The primary root produces many secondary & tertiary branches.
Distinguish between monocot leaves and dicot leaves. Monocot leaves Leaves have parallel venation
53.
Leaves have reticulate venation
Distinguish between monocot and dicot flower. Monocot flower
54.
Dicot leaves
Dicot flower
The floral whorls are found in Petals are normally in multiples of four multiples of three or five Distinguish between monocotyledonous and dicotyledonous plant. Monocotyledonous plant 1. Monocot seeds contain only one cotyledon. 2. During germination, the cotyledons remain below the soil. 3. They have fibrous root system 4. The primary root is short lived
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Dicotyledonous plant 1. Dicot seeds contain two cotyledons. 2. During germination, the cotyledons appear above the soil 3. They have tap root system 4. The primary root continues to grow
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throughout the life of the plant. 5. Roots develop from the base of the 5. The primary root produces many stem. secondary & tertiary branches. 6. Leaves have parallel venation 6. Leaves have reticulate venation 7. The floral whorls are found in 7. Petals are normally in multiples of multiples of three four or five 8. Vascular bundles are scattered 8. Vascular bundles are in a ring Draw a neat diagram of a typical dicot plant and label the parts.
56.
Classify the following into gymnosperms and angiosperms. Wheat, pinus, bean, Cycas Pinus, Cycas – Gymnosperms Wheat, bean – Angiosperms
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Write the differences between gymnosperms and angiosperms. Gymnosperms 1. They are plants in which seeds are not enclosed in fruits. 2. Cones are the reproductive structures
58.
44
Angiosperms 1. They are plants in which seeds are enclosed in fruits. 2. Flowers are the reproductive structures.
Give reason: It is slightly difficult to pull out a bean plant from the ground than a paddy plant. Bean plant has taproot system with primary root and many secondary & tertiary branches which grow deep into the soil where as paddy has fibrous root in which primary root is absent.
59.
Assume that a farmer cultivates jowar and toordal plants in the same plot at the same time. If there is insufficient rainfall which of the crops will dry faster? Why? Jowar plant will dry faster because transpiration rate is more in jowar as the leaves are broader and has fibrous root system as it cannot absorb water from deeper soil.
60.
How do you discriminate dicot from monocot plants as their seed start germinating? In monocot, cotyledons remain below the soil during germination and in dicot cotyledon appear above the soil.
61.
What are chordates? Organisms characterized by the presence of a notochord are called chordates.
62.
Mention the three unique characteristics of chordates. a) Presence of a solid supporting structure on the dorsal side of the body called notochord. b) Presence of dorsal, hollow, tubular nerve cord. c) Presence of openings in the pharynx called gill slits atleast in the embryonic stages.
63.
What are vertebrates? Chordates in which notochord is replaced by a vertebral column in the embryonic stage are called vertebrates.
64.
How are chordates classified? Chordates are classified into four sub phyla: a) Subphylum Hemichordata: Notochord is restricted to the anterior half of the body. Ex: Balanoglossus. b) Subphylum Urochordata: Notochord is present only in the tail region of the larvae. It is absent in adults. Ex: Herdmania. c) Subphylum Cephalochordata: Notochord is present through the length of the body. Ex: Amphioxus.
65.
d) Subphylum Vertebrata: Notochord is restricted only to the embryonic stage. In adults it is replaced by vertebral column. What is vertebral column? State its function.
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Vertebral column refers to a structure containing a series of ring like bones (vertebrae) arranged one above the other. It supports the body and provides attachment to the muscles. 66.
Name the five classes under vertebrates. a) Class Pisces (fishes)
b) Class Amphibia (Amphibians)
c) Class Reptilia (Reptiles)
d) Class Aves (Birds)
e) Class Mammalia (Mammals) 67.
Mention the characteristics of class Pisces. a) Members of class Pisces are commonly called fishes. b) They are aquatic vertebrates. They can be freshwater or marine forms. c) They have a streamlined body which is divided into head, trunk and tail. d) The body is covered by an exoskeleton composed of dermal scales. e) Paired and unpaired fins help in locomotion. Pair fins help in balancing. f) Respiratory organs are in the form of gills. Gill slits may be exposed or covered by operculum. g) They are cold blooded animals. Heart is two chambered with one auricle and one ventricle. It receives and pumps only de-oxygenated blood. h) Nervous system is well developed with a brain, a spinal cord and 10 pairs of cranial nerves. i) They are oviparous animals. Fertilization and development is external. j) They can be cartilaginous fishes or bony fishes based on the composition of endoskeleton. Ex: Shark, Ray fish, Hippocampus, carp, Labeo etc
68.
Draw a neat labelled diagram showing the external features of fish.
69.
How are fishes classified based on the composition of endoskeleton? Give example.
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Based on the composition of exoskeleton, fishes are classified into: a) Cartilaginous fishes – containing only cartilage in endoskeleton. Ex: Shark and ray fish b) Bony fishes – endoskeleton composed of bones Ex: Hippocampus, Carp etc. 70.
A fish which has escaped from a fisherman’s net has lost one of its pectoral fins. What difficulty will it face while swimming? Pectoral fins are one of the paired fins which help in balance. So the fish would not be able to balance properly.
71.
What are cold blooded / Poikilothermic animals? Give example. Vertebrates that keep changing their body temperature according to the changes in the environment are called cold blooded or Poikilothermic animals. Ex: Fishes, amphibians, reptiles.
72.
What are oviparous animals? Give example. Animals which lay eggs are called oviparous animals. Ex: fishes, reptiles and birds.
73.
What is meant by external fertilisation? Give example. Fertilisation taking place outside the body of the organism is called external fertilisation. Ex: Fishes, frog etc.
74.
Mention the economic importance of fishes. a) Fishes form food for humans in many countries. b) Oil obtained from the liver of shark and cod is rich in vitamin A and D. c) The dried skin of sharks is used in making polish. d) Fishes like Gambusia are used in biological control of mosquitoes.
75.
What are amphibians? Amphibians are the first vertebrates to appear on land.
76.
Mention the characteristics of amphibians. a) Amphibians are the first vertebrates to appear on land. b) They have adaptations to live both in water and on land. c) The body is divided into head, trunk and tail. Tail is absent in adult stage. d) The skin is smooth and moist. e) Locomotory organs are in the form of fore and hind limbs. Fore limbs have four digits each and hind limbs have five digits each. f) Respiratory organs are gills in larva stage, lungs, skin in adult stage. g) They are cold blooded animals with a three chambered heart. h) Nervous system consists of brain, spinal cord and 10 pairs of cranial nerves. i)
They are oviparous animals & fertilization is external.
j) They exhibit metamorphosis. Ex: Frog, Toad, Salamander, Newt, Ichthyophis (apodan)
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A frog is placed for few hours in a container whose temperature is maintained at o 30 C. Through which of the organs, respiration may not take place efficiently. Why? o
Respiration through skin is not efficient as it would not be moist at 30 C. 78.
What is meant by metamorphosis? Metamorphosis is a series of changes that take place in some organisms from larvae stage to the adult stage. Ex: Frog, Butterfly etc.
79.
What are hibernation and aestivation? The period during which some organisms bury themselves for weeks in damp places during winder to avoid extreme temperature is called hibernation. Ex: Frog, bear etc. The period during which some organisms bury themselves for weeks during summer is called aestivation (Sumer sleep).
80.
Mention the characteristics of class Reptilia. a) Reptiles are the first true terrestrial vertebrates. b) Most of them are land forms and some are adapted for life in water. c) The body is elongated, divided into head, trunk and tail. d) They have an exoskeleton in the form of epidermal scales. e) Locomotion is by fore and hind limbs. They are pentadactyl animals. f) Respiration is by lungs. g) They are cold blooded animals. Heart is three chambered. In crocodiles ventricle is incompletely divided into two chambers. h) Nervous system consists of a brain, a spinal cord and 12 pairs of cranial nerves. i) They are oviparous animals. Fertilization is internal but development is external. Ex: Turtles, tortoise, lizards, snakes
81.
How are reptiles classified? OR Name the major groups of reptiles. Give example. Reptiles are identified into four groups: a) Chelones: Turtles and tortoise. b) Lizards: House lizard, Chameleon, Calotes (garden lizard), Varanus (monitor lizards), Draco (flying lizard) c) Snakes: Viper, cobra, sea snake, Python d) Crocodiles and alligators.
82.
What are pentadactyl animals? Animals in which have five digits each in both fore and hind limbs.
83.
What is meant by internal fertilization? Fertilisation taking place inside the body of the organism is called internal fertilisation. Ex: Tortoise, snake, crocodile etc.
84.
Give reason: Crocodiles appear to shed tears.
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Crocodiles periodically eliminate some nitrogenous wastes in dissolved state through a pair of glands near their eyes. Hence they appear to shed tears. 85.
Compare the following characteristics of amphibians and reptiles. Characteristics 1. Skin 2. Digits in limbs 3. Fertilization
86.
Amphibians Soft & Moist Four in fore limbs External
Reptiles Hard & Dry Five in both fore & hind limbs Internal
Raju and Rashmi observe elongated creatures in their school. Raju infers that to be a garden lizard where as Rashmi infers that to be a salamander. Help them overcome their confusion. If the creature has a smooth and moist skin then it is an amphibian as in salamander. If the creature has dry scales then it is reptile as in garden lizard.
87.
Is there any relationship between warm blooded conditions and four chambered heart? One of the major evolutionary adaptations that allowed animals to become warm-blooded was the formation of the four-chambered heart. Four chambers mean no mixing of deoxygenated and oxygenated blood, and thus, more oxygen gets to the tissues.
88.
Mention the features of class aves. a) Members of class aves are called birds. b) They are mostly aerial, capable of flying. Some are aquatic. c) They have a streamlined (boat shaped) body. The body can be divided into head, trunk and tail. d) The body is covered by feathers. e) Locomotory organs are fore and hind limbs. Fore limbs are modified into wings for flying. The hind limbs are pentadactyl. f) The respiratory organs are a pair of lungs. g) They are warm blooded animals and heart is four chambered. h) Nervous system is well developed with a brain, a spinal cord and 12 pair of cranial nerves. i)
89.
90.
They are oviparous. Fertilization is internal and development is external.
Mention the functions of feather. a) Feathers provide protection.
b) They maintain body temperature.
c) They help in flight.
d) In some birds, it helps in sexual attraction.
How are birds classified? Give example. Birds are classified into two groups: a) Flying birds: Parrot, Hawk, Pigeon, Crow, Sparrow, Swan, Duck, Flamingo. b) Flightless birds: Ostrich, Kiwi, Rhea, Emu, Penguin etc.
91.
What are the adaptations that enable a bird to fly? OR Make a list of the main flight adaptations in birds. a) Streamlined body b) Forelimbs modified into wings. c) Arrangement of feathers on wings to provide the lift.
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Presence of flight muscles. Reduced body weight. Long bones are pneumatic. Many bones in the body are fused. Absence of teeth (replaced by beak)
What are pneumatic bones? Hollow, light, air filled bones of birds are called pneumatic bones.
93.
In which class of vertebrates pneumatic bones are found? Mention any one of its advantage. Pneumatic bones are found in class aves. It makes the body very light and fly without friction.
94.
How are the following structures modified in a bird? a) Fore limbs: Fore limbs are modified into wings that help in flight. b) Bones: Bones are hollow, light and filled with air. This makes their body light and can fly without friction.
95.
What are warm blooded or homeothermic animals? Animals that maintain a constant body temperature, irrespective of changes in the environmental temperature are called warm blooded or homeothermic animals.
96.
Mention the characteristics of class mammalia. a) Mammals are the most advanced group of vertebrates. b) They occur in a variety of habitats – terrestrial, aquatic and aerial. c) The body is divided into head, trunk and tail. Trunk is divided into an upper thorax and a lower abdomen separated by a diaphragm. d) The exoskeleton is represented by epidermal outgrowth called hairs. e) They are pentadactyl. Fore and hind limbs end in claws or nails. f) Respiratory organs are a pair of lungs. g) They are warm blooded and heart is four chambered. Aortic arch is on the left side. h) RBC are enucleate at maturity except in camels. i) Teeth are heterodont, embedded in sockets in jaw bones and occur in two sets during life. j)
Nervous system is well developed with 12 pairs of cranial nerves.
k) They are generally viviparous. Both fertilization and development takes place inside the body. A placenta is present to nourish the embryo. l)
Mammary glands are present in females secrete milk to nourish the young ones.
Ex: Platypus, Echidna, Kangaroo, Bat, Whale, Dolphins etc 97.
What is diaphragm? Diaphragm is a muscular membrane in mammals that separate the upper thorax from the lower abdomen.
98.
What are the following? a) Heterodont b) thecodont c) diphyodont
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a) Heterodont (from Greek, meaning 'different teeth') refers to animals which possess more than a single tooth. b) Thecodont is a type of teeth arrangement in which the teeth are embedded in the sockets of the jaws. c) Diphyodont refers to animals developing two successive sets of teeth, one temporary and one permanent, as in humans. 99.
What are viviparous animals?
Animals which give birth to young ones are called viviparous animals. Both fertilization and development takes place inside the body of female. 100. What is the function of placenta? The function of placenta in mammals is to nourish the embryo. 101. How are mammals classified? Give example. Mammals are classified into three major groups: a) Egg laying mammals: Platypus and echidna b) Pouched mammals: Kangaroo, Opossum c) Placental mammals: Flying mammals: Bats, Lemurs Aquatic mammals: Whales and Dolphins Carnivorous mammals: Lion, Tiger, Panther, Cat, Dog, Wolf, Fox Herbivorous mammals: Elephant, Deer Burrowing mammals: Rats, Rabbits, Shrews Primate: Monkeys, apes and humans 102. Point out any two characteristics that support the idea that Platypus is more evolved than tortoise. a) Heart of Platypus is four chambered. b) Nervous system of Platypus has spinal nerves. 103. Mention the differences between reptiles and mammals. Reptiles 1. They have exoskeleton in the form of epidermal scales 2. Most of them have three chambered heart 3. They are cold blooded animals 4. They are oviparous animals
Mammals 1. They have exoskeleton in form of epidermal hair 2. They have four chambered heart 3. They are warm blooded animals 4. They are viviparous animals
104. What was the need for vertebrates to evolve from oviparity to viviparity? The two reasons for vertebrates to evolve from oviparity (Egg-laying) to viviparity (Giving live birth) are: a) To increase the number of successful births as in viviparity the offspring is protected by the mother whereas in oviparity eggs laid can easily be eaten by other animals. Hence viviparity is selected by natural selection and they evolved to viviparity. b) In oviparity the young ones developed are mostly poor as no care is given by the mother. In viviparity the young ones get full care from the mother in terms off oxygen and
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nutrients so the young ones developed are healthier in viviparity. So they were selected by natural selection and were evolved to viviparity.
Characteristics
Pisces
Amphibians
Reptiles
Aquatic
Terrestrial & aquatic
Terrestrial
Cold blooded
Cold blooded
Cold blooded
1. Habitat 2.Body temperature 3. Exoskeleton
Scales
4. Respiratory system
Gills
5. Locomotory organs 6. Heart chambers 7. Propagation 8. Fertilization & Development
Smooth & moist Gills, lungs & skin
Fins
Limbs
2 Oviparous
3 Oviparous
External
External
Aves
Mammals
Terrestrial, aquatic & aerial Warm blooded
Terrestrial, aquatic & aerial Warm blooded
Dry and Scaly
Feathers
Hairs
Lungs
Lungs
Lungs
Limbs (Pentadactyl) 3 Oviparous Internal & External
Fore limbs – wings Hind limbs legs 4 Oviparous Internal & External
Limbs (Pentadactyl) 4 Viviparous Internal
Fill in the blanks: 1. 2. 3.
Blue green algae are included under Kingdom Monera. Golden brown algae are included under Kingdom Protista. Marine multi-cellular algae are commonly called sea weeds (Sargassum).
4.
The largest of the marine multi-cellular algae are kelps which grow to about 60m in length.
5.
An example of kelps is Microcystus.
6. 7.
The plant body of Multicellular algae is called thallus. Ulothrix is an example of green algae.
8.
The pigment present in abundance in Spirogyra/ Ulothrix is chlorophyll.
9.
The pigment present in abundance in Batrachospermum/Polysiphonia is Phycoerythrin.
10.
The red pigment present in red algae is Phycoerythrin.
11. 12.
Phycoerythrin is found in abundance in red algae. The pigment present in abundance in Sargassum/Ectocarpus is Xanthophyll.
13.
The brown pigment present in brown algae is Xanthophyll.
14. 15.
An example of an organism that contains Xanthophyll in excess is Ectocarpus. Vegetative reproduction in multicellular algae is by fragmentation of thallus.
16. 17.
Bryophytes are referred to as ‘Amphibians of plant kingdom’. The root like extensions in bryophytes is called rhizoids.
18.
The two groups of bryophytes are liverworts and mosses.
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19. 20.
An example of liverwort is Riccia/Marchantia. An example of mosses is Polytrichum/funaria.
21. 22.
A bryophyte which grows vertically to the soil surface is Polytrichum/funaria. The male gamete producing structure of bryophyte is antheridia.
23.
The female gamete producing structure of bryophyte is archegonia.
24.
The adult plant body of bryophyte is called gametophyte.
25. 26.
Mosses growing in marshy places are called bog mosses. The first terrestrial plants to develop vascular tissues are pteridophytes.
27.
The group of plants which contain vascular tissues are called tracheophytes.
28.
The adult plant body in pteridophytes is sporophyte.
29.
The independent structure developed in pteridophytes which produces male and female gametes is Prothallus.
30. 31.
Adiantum is commonly referred to as walking fern. The naked seed bearing vascular plants are gymnosperms.
32.
In gymnosperms, the male gametes are produced in structures called microsporophyll.
33. 34. 35.
In gymnosperms, the female gametes are produced in structures called megasporophyll. The reproductive structures in gymnosperms are cones. The group of plants in which the seeds are enclosed are called angiosperms.
36. 37.
The most evolved group of plants are angiosperms. In angiosperms, the seeds are enclosed in structure called fruit.
38. 39. 40.
The most significant feature of angiosperms is the flowers. The male parts of the flower Anther and Filament. The female parts of the flower are Stigma, Style and Ovary.
41.
A special branch containing a cluster of flowers is called inflorescence.
42. 43.
The group of plants that bears inflorescence is Angiosperms. The reproductive part of an angiosperm is flower.
44. 45.
47.
A feature exclusive to monocots is fibrous root system. Monocot plants have fibrous root system, parallel venation and floral whorls are in multiples of three. Dicot plants have tap root system, reticulate venation and floral whorls are in multiples of four/five. An example of a plant that has tap root system is Mustard.
48.
Organisms characterized by the presence of a notochord are called chordates.
49. 50.
The solid supporting structure on the dorsal side of the body is called notochord. The subphylum in which notochord is restricted to the anterior half of the body is Hemichordata.
51.
The subphylum in which notochord is present only in the tail region of the larvae and absent in adults is Urochordata.
52.
The subphylum in which notochord is present through the length of the body is Cephalochordata.
53. 54.
The subphylum in which notochord is restricted only to the embryonic stage is vertebrata. The fins which help fishes in balancing is paired fins.
55.
The respiratory organs of class Pisces are gills.
56.
The heart of class Pisces is two chambered.
46.
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57.
Animals which keep changing their body temperature according to the changes in the environment are called cold blooded or Poikilothermic animals.
58.
Two chambered heart is present in class Pisces.
59.
Fertilization and development in class Pisces is external.
60. 61.
Fishes receive and pump only de-oxygenated blood. Fishes are cold blooded and oviparous animals.
62.
Animals which lay eggs are called oviparous animals.
63.
Fertilisation taking place outside the body of the organism is called external fertilisation.
64.
A class of vertebrates in which both fertilization and development is external is Pisces/Amphibians.
65.
Shark is an example of cartilaginous fish.
66.
Hippocampus/Carp is an example of bony fish.
67. 68.
The fish used in the control of mosquitoes is Gambusia. Rearing of fishes is called pisciculture.
69.
The first vertebrates to appear on land are amphibians.
70. 71.
Skin of frog helps in respiration. Amphibians are Poikilothermic and oviparous animals.
72. 73.
A limbless amphibian is Ichthyophis/Apodan. Reptiles have five digits each in fore limbs and hind limbs.
74. 75.
In reptiles, fertilization is internal. In some reptiles, heart is incomplete four chambered.
76.
Among reptiles, the heart is incompletely divided into four chambers only in crocodiles.
77.
The animal group with exoskeleton in the form of epidermal scales is Reptiles.
78.
A class of vertebrates in which fertilization is internal and development is external is Reptiles/Aves.
79.
The largest lizard is Varanus.
80.
The forelimbs of class aves are modified into wings.
81.
Air filled bones of birds are called pneumatic bones.
82.
Aortic arch in birds is on right side.
83. 84. 85.
Number of cranial nerves in birds is 12 pairs. The smallest bird is humming bird. A bird capable of flying backwards is humming bird.
86.
The largest bird is Ostrich.
87. 88.
An aquatic flightless bird is Penguin. A migratory bird that can fly non-stop flight of more than 18,000km is Arctic tern.
89.
The arrangement of colourful feathers in male birds to attract females is called Plumage.
90.
The muscular membrane that divides the upper thorax and the abdominal cavities in mammals is diaphragm.
91.
The diaphragm which separates thorax and abdomen is a muscular membrane.
92. 93. 94.
A vertebrate having a diaphragm is Bat. In mammals, aortic arch is on the left side. Mammals are warm blooded animals, so their body temperature remains constant.
95. 96.
The part which nourishes the embryo is placenta. Mammals are warm blooded and viviparous animals.
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An example of a flying mammal is bat. The largest mammal is whale.
99. An egg laying mammal is Platypus/Echidna. 100. A pouched mammal is Kangaroo/Opossum. 101. The largest land mammal is Elephant. *****
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Chapter 6: Plant and Animal Tissues 1.
B6
What is a tissue? A group of cells which have a common origin, structure and function is called tissue.
2. Define an organ. A group of tissues performing a particular function is called an organ. 3.
What is an organ system? A group of organs performing a set of functions is called an organ system.
4.
Define histology. The branch of biology which deals with the study of tissues and their organization is called histology.
5.
How are plant tissues classified? Plant tissues are classified into two groups on the basis of function into: a) Meristematic tissues b) Permanent tissues
6.
What are meristematic tissues? The tissues composed of cells which keep on dividing forming new cells are called meristematic tissues.
7.
Where do meristematic tissues occur? Meristematic tissues occur in all growing regions like root tip, stem apex and buds.
8.
Mention the types of meristematic tissues & state their function a) Apical meristem: They are located at the shoot tip which makes the plant, grow taller. b) Lateral meristem: They add to girth (diameter) of the plant body.
9.
c) inter-nodal meristem: They are found at the nodes between leaves and stem. It helps in branching. Mention the features of meristematic tissues. a)
The cells have thin walls.
b) The cells divide actively and cause growth. c) The cells are closely arranged without any inter cellular spaces in between. d) 10.
The cells have a large nucleus but lacks chloroplasts.
e) Vacuoles are either small or absent. State the functions of meristematic tissues. a) Apical meristems make the plant to grow taller. b) Lateral meristems add girth to the plant body. c) Meristematic cells in vascular bundles of roots and stems bring about growth in thickness. d) The meristems found in nodes help in branching.
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B6: Plant & Animal Tissues
What are permanent tissues? The tissues formed by mature or specialized cells are called permanent tissues.
12.
Mention the features of permanent tissues. a) Permanent tissues are formed by mature or specialized cells. b) They have cell wall composed of cellulose in addition to hemicelluloses, pectin and lignin. c) They contain well developed plastids and other cell organelles. d) Vacuoles are large and prominent. e) Nucleus may be present or absent at maturity in certain types.
13.
Mention the types of permanent tissues. a) Simple tissue b) Complex tissue
14.
What is simple permanent tissue? Tissues in which the cells are of the same kind and performing common function are called simple permanent tissue.
15.
Mention the types of simple permanent tissue. a) Parenchyma
b) Collenchyma
c) Sclerenchyma
16.
What is parenchyma?
17.
Parenchyma is a simple permanent tissue in which is found in the soft parts of plants body. Mention the characteristics of parenchyma. a) The cells of parenchyma tissue are composed of thin walled living cells. b) They are least specialized. c) The cells may be round, elongated, polygonal or irregular. d) The cells are loosely arranged.
18.
e) They contain large amount of food material. Mention the functions of parenchyma. Parenchyma cells stores large amounts of food materials. If parenchyma cells contain chloroplasts, it takes part in photosynthesis. They help the leaves of aquatic plants to float.
19.
What is Chlorenchyma? Parenchyma cells containing chloroplasts are called Chlorenchyma. It takes part in photosynthesis.
20.
Mention the characteristics of Collenchyma. a) Collenchyma contains living cells and is capable of cell division. b) The cells are closely arranged without any spaces in between. c) They are thick walled at corners where the cells join. d) The cell wall is made up of hemicelluloses or pectin.
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Where do collenchyma tissues occur? Collenchyma tissues occur in pedicel and petiole of leaf.
22.
Mention the differences between parenchyma and collenchyma Parenchyma
Collenchyma
Parenchyma cells are loosely arranged Collenchyma cells are closely packed They have thin cell wall. 23.
They are thick walled at the corners
Mention the characteristics of Sclerenchyma. a) The cells of Sclerenchyma consist of thick, elongated cells, which are dead at maturity. b) The living cells of Sclerenchyma get deposited by lignin. c) They lose nucleus and protoplasm at maturity.
24.
What are fibres and sclereids? Sclerenchyma cells consisting of elongated, thread like thick walled cells are called fibres. Sclerenchyma cells consisting of hard cells found in group and having more lignin are called sclereids. The cells of sclereids are isodiametric or columnar or bone shaped or star shaped
25.
Why are fibres used in making gunny bags and ropes? Sclerenchyma fibres are flexible and elastic; hence they are used in coir industries to make gunny bags and ropes.
26.
Why sclereids are commonly called stone cells? Sclereids are hard cells found in groups and have more lignin, hence they are commonly called stone cells.
27.
Where are sclereids found? Sclereids are found in fruit wall and seed coat.
28.
Mention the differences between collenchyma and Sclerenchyma Collenchyma It contains living cells
Sclerenchyma It contains dead cells
It are capable of cell division They are not capable of cell division 29.
What is complex permanent tissue?
30.
The tissues that comprise of both living and non-living cells are called complex permanent tissues. Ex: Xylem, phloem What is xylem?
31.
Xylem is a vascular tissue which transports water and mineral absorbed by the roots to all the parts of the plant. Name the four types of xylem cells. OR what is xylem composed of? Xylem tissue is composed of:
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a) xylem parenchyma b) xylem fibres c) xylem vessels and d) tracheids. What are xylem vessels and tracheids? Xylem vessels consist of series of elongated dead cells joined together forming end to end tube like structure for conduction of water and salts.
33.
Tracheids are short structures usually found at the tip of the leaf. What is phloem? Phloem is a complex tissue which conducts food to different parts of the plant.
34.
What is phloem composed of? Phloem is composed of four types of cells. a) sieve tubes b) companion cells c) phloem fibres d) phloem parenchyma
35.
What are sieve tubes? Sieve tubes comprise of longitudinally arranged cells. The cells are joined end to end in a series. At maturity the cells lose the nucleus.
36.
What is sieve plate? Sieve plate is a plate like structure with number of pores is present in between the two cells.
37.
What are companion cells? Companion cells are living cells that are closely associated with sieve tubes. They control the passage of food through phloem.
38.
State the function of a) sieve tubes b) sieve plate c) companion cells d) phloem fibres. a) Sieve tubes: They play an important role in the conduction of food. b) Sieve plate: It allows the food to pass through the pores. c) Companion cells: They control the passage of food through the phloem. d) Phloem fibres: They provide tensile strength to the plant body.
39.
Why are xylem and phloem called vascular bundles? Since xylem and phloem occur together they are called vascular bundles.
40.
Mention the differences between xylem and phloem. Xylem
Phloem
1) It conducts water and minerals from roots to other parts of the plant body
1) It transports food from leaves to other regions.
2) It consists of dead elements
2) It consists of living elements
41.
What is epidermal tissue?
42.
Epidermal tissue is a simple permanent tissue which covers all parts of plant like stem, leaves flowers, fruits, seeds and roots. It is a protective tissue. Mention the characteristics of epidermal tissue. a) Epidermal tissue forms the covering of most parts of plant like stem, leaves flowers, fruits, seeds and roots. b) It is made up of parenchyma cells.
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c) It is living tissue. d) It is one cell thick. 43.
State the function of a) cuticle b) epidermis c) epidermis of roots a) Cuticle: In terrestrial plants, it prevents water loss. In aquatic plants, it prevents decaying of tissues of leaves and other parts. b) Epidermis: It protects the inner tissues of plants. c) Epidermis of root: It absorbs water and nutrients from the soil.
44.
What is cuticle? A waxy coating secreted by come plants is called cuticle.
45.
Give reason: In aquatic plants like lotus, the cuticle is thick. In aquatic plants like lotus, the cuticle prevents decaying of tissues of leaves and other parts.
46.
What are stomata? The tiny pores present in the epidermis of the leaves are called stomata.
47.
What is the function of stomata? Stomata regulate the passage of gasses such as oxygen and carbon dioxide and moisture into and out of the plant.
ANIMAL TISSUES 48.
How are animal tissues classified? a) Epithelial tissue b) Muscular tissue c) Connective tissue d) Nervous tissue
49.
What is epithelial tissue? Epithelial tissue is a simple tissue that covers the external and internal body surface.
50.
What is Squamous epithelium? The epithelial tissues in which the cells are thin, flat, plate like and polygonal are called Squamous epithelium. It occurs in the alveoli of lungs, oesophagus, blood vessels, capillaries and chambers of heart.
51.
When Squamous epithelium is called endothelium? When epithelium is found lining from inside, it is called endothelium.
52.
Give reason: Squamous epithelium is called ‘pavement epithelium’ Squamous epithelium look like the tiles on a floor without any space and tightly packed. Hence Squamous epithelium is referred to as pavement epithelium.
53.
State the function of Squamous epithelium.
54.
Squamous epithelium permits materials to diffuse through it. What is columnar epithelium? Where do they occur?
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The epithelial tissues composed of tall, narrow and column or pillar like cells are called columnar epithelium.
55.
They are found in the inner lining of stomach, small intestine, pharynx, larynx and oviducts. What is cuboidal epithelium? Where do they occur? The epithelium that have cube shaped cells are called cuboidal epithelium. They are found in the lining of many ducts such as pancreatic duct, salivary duct and sweat ducts.
56.
What is the function of cuboidal epithelium? Cuboidal epithelium in glands help in secretion. For example salivary gland and thyroid gland.
57.
What is ciliated epithelium? Columnar epithelial cells containing cilia on their free surface are called ciliated epithelium.
58.
State the functions of epithelium. a) Epithelium forms a thick tough barrier. It protects the underlying tissues in the skin. b) Epithelium of the skin helps in maintaining a constant body temperature. c) Epithelium is sense organs, contain receptor cells. d) Ciliated epithelium helps in the movement of materials. e) Epithelium also helps in absorption of nutrients and in excretion.
59.
What is muscular tissue? The tissues that are made up of muscle cells which help in the movement of the body are called muscular tissue.
60.
State the function of muscle fibres. Muscle fibres or myofibres are specialized cells capable of contraction and relaxation that is responsible for movement of limbs, bending of the body, movement of internal organs like heart, stomach and alimentary canal.
61.
Mention the types of muscular tissue. Based on structure, function and location, muscular tissue is divided into: a) Striped muscles
62.
b) Unstriped muscles
c) Cardiac muscles What are striped muscles? State their function. The muscles that are made up elongated, unbranched cylindrical fibres with stripes or striations or cross bands are called striped muscles.
63.
They are voluntary muscles and help in locomotion. Give reason: Striped muscles are called ‘skeletal muscles’.
64.
Striped muscles are usually attached to the bones. Hence they are called skeletal muscles. What are unstriped muscles? Give example.
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The muscles that are made up of spindle shaped, elongated muscle fibres without stripes (cross bands) are called unstriped muscles.
65.
They are also called smooth muscles. They are involuntary muscles. Example: The peristaltic movements of oesophagus, intestine and stomach are due to unstriped muscles. They are also found in kidneys, blood vessels and glands. What are voluntary and involuntary muscles? The muscles that are under the will of the organism are called voluntary muscles. The muscles that are not under the will of the organism are called involuntary muscles.
66.
Write the structural and functional differences between striped and unstriped muscles. Striped muscles
67.
Unstriped muscles
1) They are cylindrical in shape
1) They are spindle shaped
2) They have stripes or striations
2) They do not have stripes or striations
3) They are voluntary muscles
3) They are involuntary muscles
4) They help in locomotion
4) They help in peristaltic movement of oesophagus, small intestine etc.
Mention the characteristics of cardiac muscles. a) Cardiac muscles are composed of branched fibres that have stripes or bands. b) The branches are connected with one another in a cris-cross form. c) They are involuntary muscles d) They do not fatigue easily. e) They are found only in the heart.
68.
State the function of cardiac muscles. Cardiac muscles are responsible for the contraction and relaxation of the heart. It makes the heart beat continuously throughout one’s life.
69.
How is the heart able to function continuously without any rest in between?
70.
The muscles of the heart are made up of cardiac muscles which do not fatigue easily. Hence they are able to function continuously without rest. Name the muscles that help in the following muscular movement. Walking – Locomotor Speaking – muscles of vocal cord
Respiration – movement of diaphragm Expression of emotions – facial muscles
Propulsion of food in alimentary canal – Smooth muscles
71.
Pumping of blood – cardiac muscles Urination – contraction of smooth muscles of the urinary bladder. What are connective tissues? The tissues that connect various other tissues of the body and provide support are called connective tissues. They consist of cells, fibres enclosed in a ground substance called matrix.
72.
Mention the types of connective tissues.
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On the basis of the nature of the matrix, connective tissues are classified into: a) Loose connective tissues b) Dense connective tissues c) Fluid connective tissues. 73.
Why connective tissues are called ‘binding tissues’? Since connective tissues connects or binds other tissues, it is also called binding tissue.
74.
What are loose connective tissues? Mention their types. The tissues in which the fibres in the matrix are loosely arranged is called loose connective tissues. They are of three types. a) areolar tissue b) adipose tissue c) reticular tissue
75.
What is areolar tissue? Where are they found? The tissues that are found below the skin in which the fibres are loosely connected and having air spaces are called areolar tissue. They are found in both dermis and sub-cutaneous layers of the skin. It is also found in and around mucous membrane and around blood vessels and nerves.
76.
Name the three types of fibres found in the areolar tissue. a) White fibres or collagen fibres found in groups. b) Yellow fibres or elastic fibres found singly. c) Reticular fibres, forming a network.
77.
Name the different types of cells found in areolar tissue and state their function. Fibroblasts: They are large, flat, highly branched. They secrete and maintain fibres. Plasma cells: They are oval in shape and have small nucleus. They produce antibodies. Macrophages: They are amoeboid in shape. They defend against micro-organisms. They ingest the micro-organisms. Mast cells: They are large cells having a spherical nucleus with granular cytoplasm. They are associated with secretion of substances like serotonin, heparin and histamine.
78.
Why are areolar tissues called so? Areolar tissues have air spaces in between the fibres, hence it is referred to as areolar tissue.
79.
How does areolar tissue help in body defence? Cells of areolar tissues produce antibodies and also defend against micro-organisms. They also ingest the micro-organisms. Hence they help in body defence.
80.
What is adipose tissue? The tissues that have closely packed fat cells are called adipose tissue.
81.
State the functions of adipose tissues. Adipose tissues stores nutrients and used as and when the body requires.
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It provides insulation against cold. It protects certain organs by acting a s shock absorbers.. 82.
State the function of reticular tissue.
83.
Reticular tissue provides frame work for organs like liver, spleen, bone marrow, tonsils and mucous membrane, lining of the respiratory tract and alimentary canal. What are tendons? Tendons are cord like, inelastic structures that joins the skeletal muscles to bones or cartilage.
84.
What are ligaments? Ligaments are elastic fibres which connect bones to other bones. They help in movement of bones.
85.
Mention the differences between tendons and ligaments. Tendons They are inelastic
Ligaments They are elastic
They join muscles to bones or cartilage They join bones with other bones 86.
What are dense connective tissues? The connective tissues consisting of hard matrix are called dense connective tissues.
87.
State the functions of dense connective tissues. They form the skeletal system of the body providing an internal supporting frame work. They enclose the internal organs. Ex: Skull protects brain, eyes, ears, nose.
88.
Name the organs protected by the following: a) Skull – Brain, eyes, ears and nose b) Ribcage – heart and lungs c) Vertebral column – spinal cord
89.
d) Pelvic girdle – organs of digestion, excretion, reproduction and other glands. What is cartilage tissue?
90.
Cartilage is a specialized connective tissue which is non-porous, elastic and flexible. Mention the features of cartilage tissue. a) Cartilage consists of translucent or glassy matrix composed of chondrin. b) It has cells called chondrocytes.
91.
c) The space in chondrocytes is called lacunae. d) Cells may be single or in groups of 2 or 3. State the function of chondrocytes.
92.
Chondrocytes secrete the matrix. Give reason: White and yellow fibres in cartilage are not easily visible. The refractive index of the fibres and the matrix are same. Hence they are not easily visible.
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93.
What is perichondrium? What is its function?
94.
The cartilage is externally surrounded by a connective tissue layer called perichondrium. Its function is to provide nutrients and oxygen to chondrocytes. Where are the cartilage found in the body? a) Cartilage is present in C shaped rings in the trachea, bronchi.
95.
b) It is present in larynx, epiglottis, walls of Eustachian tube and pinna. c) It is present in between the vertebrae in the vertebral column. What is the function of cartilage in between vertebrae in the vertebral column?
96.
The cartilage present between the vertebrae in the vertebral column helps in bending and stretching movements. What is bone tissue? Bone is strong, non-flexible, porous connective tissue. The matrix of a bone consists of collagen fibres, proteins, inorganic salts like calcium phosphate, chlorides of potassium, sodium and magnesium.
97.
What is bone marrow? The long and strong bones of limbs are filled with a fluid called bone marrow. The function of bone marrow is to produce blood cells.
98.
Explain the Haversian system of bone. a) The structural unit of bone tissue is called Haversian system. b) It consists of a central Haversian canal containing blood vessels and nerves. c) It is surrounded by a matrix called ossein. d) Ossein contains collagen fibres and mineral salts chiefly calcium phosphates. e) Ossein is arranged in the form of concentric layers called lamellae. f) There are fluid filled spaces between lamellae called lacunae. g) There are fine canals interconnecting the lamellae called canaliculi. h) The osteocytes are interconnected by protoplasmic strands extending through the canaliculi. i)
99.
Two adjoining Haversian canals a connected by transverse canals called Volkmann’s canal.
What are these? a) Ossein: The matrix surrounding the Haversian canal is called Ossein. b) Lamellae: The concentric layers of Ossein are called lamellae. c) Lacunae: the fluid filled spaces between lamellae are called Lacunae. d) Canaliculi: The fine canals interconnecting adjoining lacunae are called Canaliculi.
e) Volkmann’s Canal: The transverse canals connecting two Haversian canals is called Volkmann’s canal. 100. Differentiate between cartilage and bone Cartilage
Bone
1. It is soft & flexible
1. It is hard & rigid
2. It is non-porous
2. It is porous
3. Matrix consists of collagen fibres
3. Matrix consists of collagen fibres, proteins and inorganic salts.
4. There is no direct supply of blood to
4. There is a direct supply of blood to
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101. Name the fluid connective tissues. Blood and lymph are the fluid connective tissues. 102. What is blood plasma? The fluid matrix of blood tissue is called blood plasma. 103. Name the constituents of blood. Blood consists of blood cells like Red Blood Cells, White Blood Cells & platelets. 104. Write short notes on Red Blood Cells. a) Red Blood Cells are involved in supplying of oxygen to every cell in the body. b) They remove carbon di-oxide from the cells and transport it to lungs. c) The number of RBC’s vary from 4.5 to 5.5 million cells/cubic mm of blood. d) They are circular, biconcave discs. e) They have a life span of 100 to 120 days. f) They originate in the bone marrow. g) They enclose an iron containing pigment called haemoglobin. h) It helps in the transport of oxygen. 105. State the function of a) RBC b) WBC c) Platelets a) RBC: They supply oxygen to cells of the body and remove carbon di-oxide from the cells. b) WBC: They help in body defence. c) Platelets: They help in clotting of blood. 106. What is lymph? What are lymph nodes? Lymph is a colourless fluid that has been filtered out of the blood capillaries. Lymph consists of white blood cells. Lymph enters a set of capillaries which form the lymph glands or lymph nodes. 107. Mention the functions of lymph. a) Lymph produces antibodies that form a part of immune system b) It contains a type of white blood cells or phagocytes which remove bacteria and foreign bodies from the tissues. 108. State one function of phagocytes present in lymph tissue. Phagocytes remove bacteria and foreign bodies from the tissues. 109. What is a nerve cell or neuron? Neuron is the structural and functional unit of nervous tissue. 110. State any one function of nerve tissue. a) It responds to external & internal stimuli of the body. b) Nervous tissue transmits nerve impulses from all parts of the body to nerve centers.
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111. Briefly explain the structure of neuron. Neurons are the structural and functional unit of nervous tissue. Each neuron has a cyton or cell body consisting of central nucleus and cytoplasm. Short projections arise from the cell body called dendrites. A long, cylindrical fibre called axon extends from the cell body. The axon is covered by a fatty sheath called Myelin Sheath. The axon ends in branches. 112. What are dendrites? The short projections arising from the cell body is called dendrites. 113. What is axon? An axon is a single long, cylindrical fibre extending from a cell body 114. What are telodendrons? The axon ends in a bunch of branches called telodendrons. 115. What is Myelin sheath? They fatty sheath covering on the axon is called Myelin sheath. 116. Draw a neat diagram showing the structure of a neuron and label the parts.
Fill in the blanks: 1. The branch of biology which deals with the study of tissues and their organization is called histology. 2. Plants exhibit only tissue level of organisation. 3. The tissues which are meant only for growth is meristematic tissue. 4. The tissues composed on cells which divide forming new cells are meristematic tissues. 5. The meristems which help in branching are nodal meristems.
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6. The meristems which help in increasing the girth of the plant is lateral meristems, 7. The tissues formed by mature or specialised cells are called Permanent tissues. 8. The tissue found in soft parts of plant like root, stem, and leaves is Parenchyma. 9. Parenchyma containing chloroplasts are called Chlorenchyma. 10.
Parenchyma with large inter-cellular spaces filled with air is called aerenchyma.
11.
The cell wall of collenchyma is made up of hemicelluloses or pectin.
12. 13.
Collenchyma generally occurs in pedicel or petiole. The hard shell of coconut is composed of Sclerenchyma.
14.
The cells of Sclerenchyma lose nucleus and protoplasm at maturity.
15. 16.
The tissues used in coir industries to make gunny bags and ropes are Sclerenchyma (fibres). Sclereids are referred to as stone cells.
17. 18.
The type of permanent tissue found in fruit wall and seed coat is Sclerenchyma. The cells closely associated with sieve tubes are companion cells.
19.
The outermost covering of the plant body called epidermal tissue.
20. 21. 22.
The tissue referred to as ‘skin of the plant body’ is epidermal tissue. The waxy coating on the plant body is called cuticle. The openings in the epidermis of plants are called stomata.
23. 24.
The tissues found in the inner and outer lining of the body are called epithelial tissues. The epithelium consisting of flat plate like cells is called Squamous epithelium.
25. 26.
The epithelium referred to as pavement epithelium is Squamous epithelium. The type of epithelium found in the alveoli of lungs, oesophagus, blood vessels etc is Squamous epithelium. The type of epithelium referred to as endothelium is Squamous epithelium. The epithelium containing elongated, tall, pillar like cells is called columnar epithelium,
27. 28. 29.
The type of epithelium found in the inner lining of stomach, small intestine, pharynx, larynx and oviducts is columnar epithelium.
30.
The epithelium consisting of cube shaped cells is cuboidal epithelium.
31.
The type of epithelium found in the lining of ducts is cuboidal epithelium.
32. 33. 34.
The type of epithelium found in the lining of salivary glands is cuboidal epithelium. The type of epithelium found in the lining of ducts is cuboidal epithelium. The type of epithelium which helps in secretion is cuboidal epithelium.
35.
The type of epithelium which have cilia on their free surface is ciliated epithelium.
36. 37.
The muscles that are elongated, cylindrical and unbranched are called striped muscles. The muscles that are elongated, spindle shaped are called unstriped muscles.
38.
The muscles that are referred to as skeletal muscles are striped muscles.
39.
The muscles that are under the control of the organism are called voluntary muscles.
40.
The muscles that are not under the control of the organism are called involuntary muscles.
41. 42. 43.
The muscles that are found only in the heart are cardiac muscles. The muscles that are involved in the expression of emotions are facial muscles. The muscles that are involved when we speak are muscles of vocal cord.
44.
The muscles that are involved in propulsion of food from alimentary canal are smooth muscles.
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45.
The muscles that are involved in pumping of heart are cardiac muscles.
46.
The muscles that are involved during urination are smooth muscles of urinary bladder.
47.
The tissues which connect various other tissues of the body and provide support are called connective tissues.
48.
Connective tissues are also called binding tissues.
49.
The tissues in which the fibres in the matrix are loosely arranged is called loose connective tissue.
50. 51.
The tissue that is found in the dermis and sub-cutaneous layers of the skin are areolar tissue. The function of fibroblasts is to secrete and maintain fibres.
52. 53.
The function of plasma cells is to produce antibodies. The function of macrophages is to ingest the micro-organisms.
54.
Secretion of Serotonin, heparin and histamine is the function of mast cells.
55. 56. 57.
The tissue that consists of closely packed fat cells is adipose tissue. The tissues which act as shock absorber is adipose tissue. The tissue which provides insulation against cold is adipose tissue.
58. 59.
The tissues which connect muscles to bones or cartilage are tendons. The tissues which connect one bone to another is called ligament.
60.
The tissue which helps in movement of bones is ligament.
61. 62.
Connective tissues consisting of hard matrix are called dense connective tissue. Brain, ears, eyes, nose and other organs of face are protected by skull.
63.
Heart and lungs are protected by ribcage.
64. 65.
Spinal cord is protected by vertebral column. The organs of digestion, excretion and reproduction are protected by pelvic girdle.
66. 67.
The matrix of cartilage is secreted by chondrocytes. Cartilage is externally surrounded by a connective tissue called perichondrium.
68.
The C shaped ring of trachea and bronchi are made of cartilage.
69.
Cartilage brings about bending and stretching movements of vertebral column.
70.
The long and strong bones of limbs are filled with a fluid called bone marrow.
71. 72. 73.
The function of bone marrow is to produce blood cells. The structural unit of bone tissue is Haversian system. The Haversian system is surrounded by a matrix called Ossein.
74.
Ossein arranged in the form of concentric layers is called lamellae.
75. 76.
Between lamellae, the fluid filled spaces are called lacunae. Adjoining lamellae are interconnected by fine canals called canaliculi.
77. 78.
Adjoining Haversian canals are connected by transverse canals called Volkmamn’s canal. Smallest bone in the human body is in the middle ear.
79.
85% of inorganic component of the bone is calcium phosphate.
80. 81. 82.
Blood is a connective tissue. Blood and lymph are fluid connective tissues. The matrix of blood is called plasma.
83. 84.
The number of RBCs varies from 4.5 to 5.5 million cells/cubic mm of blood. The lifespan of RBC is 100 to 120 days.
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85. 86.
The number of WBCs varies from 6000 to 10,000 cells/cubic mm of blood. The number of platelets in a healthy human adult is 2,50,000 in 1cm3 of blood.
87. 88.
The function of platelets is to help in clotting of blood. There is absence of RBC in lymph.
89.
Lymph flows through a set of capillaries called lymphatic capillaries.
90.
The structural and functional unit of nerve tissue is neuron.
91. 92.
The short projections arising from the cell body of neuron are called dendrites. The long extension of the cell body of the neuron is called axon.
93.
The axon ends in a bunch of branches called telodendrons.
94.
The axon is covered by a fatty sheath called Myelin Sheath.
95.
The fastest nerve impulse in humans travel at eight metres per second.
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Chapter 7: Microbial Diseases 1.
B7
What is Chikungunya? Chikungunya is a disease caused due to alpha virus also known as Chik-V.
2. How is Chikungunya transmitted? Chikungunya is transmitted to humans by a mosquitoes belonging to the species Aedes aegyptii. 3.
Write the symptoms of Chikungunya. a) Symptoms of Chikungunya include: o
b) Fever up to 40 C or 104F. c) Rashes on the trunk region and occasionally on the limbs. d) Severe pain in multiple joints. e) Headache, conjunctivitis and slight photophobia f) Fever may last for two to five days. g) Joint pain may last for much longer period some times for years. 4.
How does Chikungunya spread? The mosquitoes(Aedes aegyptii) breed in stagnant water. They bite during the day. They are most active early in the morning and late afternoon.
5.
Why do Chikungunya cases increase during monsoon season? During monsoon season, rain water collects in ditches, coconut shells; waste containers, unused pots etc. become breeding ground of mosquitoes. Hence the number of cases of Chikungunya cases increase during monsoon.
6.
Mention the methods to prevent the spread of Chikungunya. a) Avoid stagnation of water especially during monsoon season. b) Clear water collected in coconut shells, waste containers like unused pots etc. c) Control the disease by killing immature larvae of mosquitoes by spraying insecticides. d) Wear long sleeved and full length clothes to avoid mosquito bites. e) Wear light coloured clothing. f) Use safe mosquito repellents and mosquito nets to prevent mosquito bite.
7.
What is Dengue? Dengue is an infectious tropical disease caused by Dengue virus.
8.
How does Dengue fever spread?
9.
Dengue fever is transmitted by the mosquito (Aedes aegyptii). Mention the symptoms of Dengue fever. a) At the onset of the disease – headache, fever, exhaustion, severe muscle and joint pain, swollen glands and rashes. b) Bleeding gums, severe pain behind the eyes, redness in palms and soles.
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What is the main symptom of Dengue fever? Reduced platelet count is the main symptom of Dengue fever. The platelet count in normal healthy person is 2,50,000 in cm3 of blood but in a person with Dengue fever the platelet count will be 1,00,000 in cm3 of blood.
11.
How does Dengue infect humans? a) Mosquito (Aedes aegyptii) bites an infected person. b) Virus enter the body of mosquito c) Infected mosquito bites a healthy person. d) Healthy person is infected by Dengue virus.
12.
How can we identify the mosquito (Aedes aegyptii)? The mosquito (Aedes aegyptii)can be easily recognized by white spots on the body and the leg region. It rests indoors in dark places.
13.
Name the mosquito responsible for spreading both Chikungunya and Dengue fever.
14.
Aedes aegyptii Give reason: A person becomes susceptible to Chikungunya and Dengue infection. The mosquito (Aedes aegyptii) which spreads both Chikungunya and Dengue bites during the day time and it is likely to go unnoticed as it does not cause skin irritation. Hence a person is more susceptible to Chikungunya and Dengue fever easily.
15.
What is the cure for Dengue fever? A decoction prepared using young leaves of papaya given to Dengue patients can cure it because it increases the number of platelets.
16.
What is bird flu or Avian flu? Bird flu or Avian influenza is a viral fever that infects humans.
17.
How does bird flu or Avian flu spread? Avian flu spreads by touching contaminated surfaces. Birds infected with this flu continue release the virus in their faeces and saliva for as long as 10 days.
18.
Mention the symptoms of Avian flu. Infection in humans cause symptoms like – cough, diarrhoea, breathing difficulty, fever more than 38oC, headache, muscle pain, running nose and sore throat.
19.
Mention the steps that can be taken to prevent the spread of bird flu. a) Travellers should avoid visits to bird markets of infected areas. b) People who work with birds should use protective clothing and special breathing masks.
20.
c) Partially cooked and uncooked meat should be avoided. What is meant by STD? STD stands for Sexually Transmitted Disease. Sexually transmitted diseases (STDs) are infections that can be transmitted through sexual contact with an infected individual. Ex: Syphilis, Gonorrhea, Genital Warts, Genital Herpes, Hepatitis B, AIDS.
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What is Syphilis? How is it caused? Syphilis is a sexually transmitted Disease (STD) caused by the bacterium – Treponema Pallidum.
22.
How does Syphilis spread? Syphilis is transmitted through sexual contact with infected person. From mother to foetus through placenta or direct contact with infected blood.
23.
Write the symptoms of Syphilis. a) Ulcers appear on the nose, roof of mouth and lower leg. b) Damage to organs like brain, nerves, eyes, heart, blood vessels, liver, bones and joints. c) Difficulty in coordinating muscular movements, paralysis, numbness, gradual blindness and memory loss.
24.
How can Syphilis be prevented? Transmission of Syphilis can be prevented by avoiding sexual contact with infected person.
25.
What is Gonorrhea? Gonorrhea is a sexually transmitted disease caused by the bacterium Neisseria gonorrhoeae.
26.
Write the symptoms of Gonorrhea. a) In Men, burning sensation with urination and discharge from genitals. b) In women vaginal discharge and pelvic pain.
27.
How can Gonorrhea be prevented? Transmission of Gonorrhea can be prevented by avoiding sexual contact with infected person.
28.
What are genital warts? Genital warts are soft growth on the skin and mucus membranes of the genitals.
29.
What causes genital warts? Genital warts are caused by a virus Human Papilloma Virus (HPV).
30.
How can the transmission of genital warts be prevented? a) Avoiding any kind of sexual contact with infected person. b) Women in the age group 9 – 26 years can get vaccinated to protect against HPV.
31.
What is genital herpes? Genital herpes is a sexually transmitted disease caused by Herpes simplex virus type – 1 (HSV – 1) and type–2(HSV – 2).
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Write the symptoms of genital herpes. a) Appearance of one or more blisters on or around the genitals or rectum. b) The blisters break leaving tender ulcers or sores. It may take two to four weeks to heal. c) Outbreak of blisters appear for weeks or months after the first.
33.
How can genital herpes be prevented? Transmission of genital herpes can be prevented by avoiding sexual contact with infected person.
34.
What is hepatitis B? Hepatitis means liver infection or cirrhosis.
35.
How is hepatitis B caused? Hepatitis is caused by infection of hepatitis B virus (HBV). It is highly concentrated in blood. Other fluids which contain less amount of virus are body fluids like saliva, wound exudates, semen and vaginal secretions. It is transmitted by exposure to infected blood or body fluids, sexual contact with infected person and drug abuse.
36.
How can hepatitis B infection be prevented? Temporary protection for 3 to 6 months from HBV infection can be obtained by taking a vaccine called Hepatitis B Immune Globulin (HBIG).
37.
What is AIDS? AIDS stands for Acquired Immuno deficiency Syndrome. It is a sexually transmitted disease.
38.
How is AIDS caused? AIDS is caused by the Human Immuno Deficiency Virus (HIV).
39.
Explain the structure of a HIV. A HIV cell is spherical in shape containing RNA as its genetic material. It is covered by a membrane made up of two layers of fatty material. Inside the membrane there is a core made up of proteins. In the centre of the core, RNA is present along with the enzyme reverse transcriptase. This enzyme acts as a catalyst on RNA helping in the synthesis of DNA in the host cell.
40.
What is meant by retro virus? Virus which contains RNA as genetic material is called as retro virus.
41.
To which group of viruses does HIV belong? HIV belongs to retro group of viruses which are capable of giving rise to DNA.
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42.
Draw a neat labelled diagram showing the structure of a HIV cell.
43.
Mention the genetic material and enzyme present in HIV.
74
The genetic material present is RNA. The enzyme present is reverse transcriptase. 44.
Give reason: The symptoms of AIDS or HIV take number of years to appear. When HIV enters into a host cell, the RNA helps in synthesis of DNA. This HIV gets adapted to the host body so well that the body cells fail to identify the virus as intruder. Thus, the symptoms make take years to appear.
45.
Give reason: A HIV affected person is attacked by various diseases. HIV destroys the natural immunity of the body. This leads to secondary infections. Thus, the affected person is attacked by various contagious diseases.
46.
What is meant by HIV +ve? A HIV infected person is termed as HIV +ve.
47.
Mention the modes of transmission of HIV. a) Sexual contact with an infected person. b) Transfusion of infected blood. c) Sharing of needles and syringes with an infected person. d) From infected mother to the embryo through placenta. e) Infected mother breast feeding her infant.
48.
How does HIV transmit from mother to infant? A HIV +ve mother can transmit HIV to the embryo through placenta. It is also transmitted when a HIV +ve mother breast feeds her child.
49.
Give reason: AIDS by itself is not a disease by a syndrome. AIDS patients show several symptoms which occur at the same time. So AIDS itself is not a disease but a syndrome.
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Why mosquitoes do not spread AIDS? HIV multiplies only in lymphocytes and infection is acquired through contact with body fluids like semen, blood and vaginal fluids. The virus responsible for the AIDS infection is regarded as food to the mosquito and is digested along with the blood meal. As a result, mosquitoes that ingest HIV-infected blood digest that blood within 1-2 days and completely destroy any virus particles that could potentially produce a new infection. Since the virus does not survive to reproduce transmission of HIV by mosquitoes is not possible.
51.
Mention the methods by which AIDS/HIV is not transmitted. AIDS/HIV does not spread by: a) Kissing or hugging an infected person. b) Using public toilets, swimming pools c) Mosquitoes, flies and other insects. d) Travelling with infected person. e) Shaking hands with infected person. f) Living and working with infected person. g) Using bed sheets, towels, combs used by infected person. h) Touching door knobs used by infected person. i)
52.
Sharing food, utensils used by infected person.
Mention the methods of prevention of AIDS/HIV. As there is still no medicine for AIDS, the only way is to avoid HIV infection. The safest way to protect from HIV infection is to practice 3A’s: a) b)
Avoiding sex with multiple partners/ infected person. Abstaining from drug use or other skin piercing instruments unless it is absolutely necessary.
c) 53.
Avoiding contact with body fluids of infected person.
Give reason: AIDS is an infectious disease but not a communicable disease. AIDS is an infectious disease but not transmitted through air, water & food. So it is not a communicable disease.
54.
A boy who is HIV +ve was denied admission in a school. The court did not approve this. What scientific justification do you make on this? HIV is not transmitted by touching, sharing common toilet, playing together or by sharing / eating food together. Hence schools should not deny admission.
Fill in the blanks: 1.
The word Chikungunya is derived from Makonde language.
2.
The meaning of Chikungunya in Makonde language is that which bends up.
3.
Joint pain is one of the symptoms of the viral disease Chikungunya.
4.
Chikungunya is infection caused due to alpha virus or Chik-V.
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5. 6.
Chikungunya is spread by mosquito Aedes aegyptii. Dengue fever is also known as break-bone fever.
7. 8.
Dengue fever is transmitted by mosquito Aedes aegyptii. Dengue is more severe in people with weak immune system.
9.
The main symptom of Dengue fever is reduced platelet count.
10.
A decoction prepared using young leaves of papaya is used as cure for Dengue fever.
11. 12.
STD stands for Sexually Transmitted Disease. Syphilis is transmitted by the bacterium Treponema Pallidum.
13.
Gonorrhea is transmitted by bacterium Neisseria gonorrhoeae.
14.
Genital warts are caused by virus Human Papilloma Virus (HPV).
15. 16.
Genital Herpes is caused by Herpes Simplex Virus type –1 and type – 2. The organ which is affected by Hepatitis B is liver.
17.
The vaccine to prevent hepatitis B is HBIG.
18. 19.
HBIG stands for Hepatitis B Immune Globulin. HBIG provides protection against Hepatitis B for 3 – 6 months.
20. 21.
AIDS stands for Acquired Immuno Deficiency Syndrome. AIDS was recognised for the first time in USA in 1981.
22. 23.
HIV stands for Human Immuno deficiency Virus. In India, the first AIDS patient was identified at Chennai in 1987.
24. 25.
The enzyme present in HIV is Reverse transcriptase. The group to which HIV belongs is retrovirus.
26.
The most dreadful viral disease that has affected human society in recent decades is Hepatitis B.
27.
The genetic material in HIV is RNA.
28. 29.
HIV is covered by a membrane made up of two layers of fatty material. Hepatitis B is dangerous since it damages the liver.
30.
The enzyme reverse transcriptase helps in the synthesis of DNA in the host cell.
*****
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Chapter 8: Types of Motion 1.
P8
Define motion. Motion is a natural event that involves a change in the position or location of an object with time.
2.
What is need for the study of motion of objects? Study of motion of objects is needed because: a) Chemical reactions are possible only because of movement and collision. b) Geologists use physics of waves to study and measure the tectonic plate motion and predict earthquakes. c) Cosmologists use physics to study the behaviour of heavenly bodies. d) Doctors use it to map the flow of blood to check whether the arteries are blocked.
3.
Give examples of motion that is not easily detected. a) Constituents of solid are in a state of continuous vibration, not visible to the naked eye. b) The revolution and spin of the earth is not detected inspite of their high speed. c) Theory of plate tectonics tells us that the continents are drifting at the slow speed.
4.
How is a wave produced? A wave is produced by the periodic disturbance at a point in a medium.
5.
How is the energy transferred in a wave without transfer of particles of the medium? When a wave propagates in a medium, the particles of the medium vibrate about their mean position and the energy is transferred without the transfer of particles of the medium.
6.
Do the particles of the medium in which a wave moves travel along with the wave? Explain with an example. OR Take some water in a trough and float a piece of cork in it. When the water is disturbed, the cork moves up and down but not forward. Why? When a wave propagates in a medium, the particles of the medium vibrate about their mean position and the energy is transferred without transfer of the particles of the medium. For example: Take some water in a trough and float a piece of cork in it. When the water is disturbed, the cork moves up and down but not forward.
7.
What is wave velocity? Velocity of the disturbance transmitted in a medium is called wave velocity.
8.
On what factor does the velocity of wave depend? Velocity of wave depends on the nature of the medium and not on the energy content.
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Write the relation between wavelength and frequency of a wave. Wavelength and frequency are related by the equation V = n λ
10.
What is wavelength and frequency of a wave? The distance between two consecutive compressions or rarefaction is called wavelength. The number of waves in unit time is called frequency of wave.
11.
Write the relation between time period and frequency of the wave. Time period and frequency of the wave are related by the equation T=
12.
1 n
If we double the frequency of a vibrating object, what happens to its time period? As time period is inversely proportional to its frequency, when the frequency is doubled, its time period becomes half. If the original time period is T =
13.
1 1 , When it frequency is doubled it becomes T = n 2n
What are mechanical waves? Give example. The waves which need a material medium for their propagation are called mechanical waves. They can travel only in material medium like water, air and earth. Ex: Sound waves
14.
What are transverse waves? The waves in which particles vibrate in the direction perpendicular to the direction of wave propagation are called transverse waves. Ex: Visible light, ultraviolet waves, x-rays etc.
15.
What are longitudinal waves? The waves in which particles vibrate along the direction of the propagation are called longitudinal waves. Ex: Sound waves.
16.
Distinguish between transverse waves and longitudinal waves. Transverse waves 1. Particles vibrate in the direction perpendicular to the direction of wave propagation. 2. The wave propagates in the form of crests and troughs. 3. One crest and one trough constitute a wave. Ex: Light waves, waves on the surface of water, waves on a string
17.
Longitudinal waves 1. Particles vibrate along the direction of the propagation. 2. The wav propagates in the form of compressions and rarefactions. 3. One compression and one rarefaction constitute a wave. Ex: Sound waves, vibration in gases, oscillation of spring.
What are electromagnetic waves? The waves associated with electric and magnetic fields, resulting from the acceleration of an electric charge are called electromagnetic waves. They require no material medium for their propagation. Ex: Visible light, Ultraviolet light, x-rays, radio waves etc.
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In wave motion, energy is transmitted from one place to another. Can the wave energy be transformed into any other form? Yes, movement of large quantities of water up and down in the seas and oceans in the form of waves can be converted into mechanical energy and electrical energy.
19.
When a rope is tied to hook and one end of the rope is moved up and down, a wave starts from the point where it is being held and moves to the other end. Identify the wave produced. As the rope is moving up and down i.e. perpendicular to the direction of propagation of the wave, it is transverse waves. -1
20.
A 50Hz vibrator produces air waves that speed out at 340ms . What is a) its time period? b) its wavelength?
21.
The wavelength of a longitudinal wave is 1cm and its velocity in air is 330ms . Find the frequency of the wave.
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22.
The frequency of a sound wave is 256Hz and its wavelength is 1.2m. Calculate its wave velocity.
23.
If the frequency of a transverse wave is 10Hz and the distance between the two consecutive wave crests is 2m. Calculate the wave speed.
24.
Define simple harmonic motion and give examples.
80
Motion which repeats after regular intervals of time is called simple harmonic motion. Ex: Oscillation of simple pendulum, vibration of a tuning fork. 25.
Define the following with reference to simple harmonic motion. a) Amplitude b) Oscillation c) Time period a) The maximum displacement of the particle on either side of the equilibrium position is called amplitude. b) One complete to and fro motion of the particle about its mean position is called oscillation
26.
c) The time taken by the body to complete one oscillation is called time period (T) Give example of simple harmonic motion. a) Oscillation of simple pendulum. b) When a tuning fork is hit against a rubber pad, its prongs execute simple harmonic motion. c) When the load is attached to the lower end of a spring suspended from a support is pulled and released, it executes simple harmonic motion.
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d) When the bus is in the clutch gear, we see a vibration and hear the sound produced by it. This is simple harmonic motion. 27.
Give the practical applications of simple harmonic motion. a) Simple harmonic motion of a pendulum was used for the measurement of time. b) Tuning the musical instrument is done with the vibrating tuning form which executes simple harmonic motion. c) Study of waves is indirectly the study of simple harmonic motion. d) The study of molecules is made with the help of vibration spectrum.
28.
Write the formula to find the time period of a simple pendulum. Time period of a simple pendulum is calculated using the formula T= 2π
l g
Where l is the effective length of the pendulum. g is the gravitational acceleration.
Fill in the blanks: 1.
A natural event that involves a change in the position or location of an object with time is called motion.
2.
Chemical reactions are possible only because of movement and collision.
3.
Geologists use physics of waves to study and measure the tectonic plate motion and predict earthquakes.
4. 5.
Cosmologists use physics to study the behaviour of heavenly bodies. A wave is produced by the periodic disturbance at a point in a medium.
6.
Velocity of the disturbance transmitted in a medium is called wave velocity.
7. 8.
Speed / Velocity of wave depends on the nature of the medium. Velocity of wave does not depend on the energy content.
9.
Wavelength and frequency are related by the equation V = n λ
10.
The distance between two consecutive compressions or rarefaction is called wavelength.
11. 12.
The S.I unit of wavelength is metre (m). The number of waves occurring in unit time is called frequency.
13.
The unit of measurement of frequency of a wave is hertz(Hz).
14.
Time period and frequency of the wave are related by the equation T =
15.
Very large distances which could not be measured were called celeris.
16.
Waves which need a material medium for their propagation are called mechanical waves.
17.
The waves in which particles vibrate in the direction perpendicular to the direction of wave propagation are called transverse waves.
18.
The waves in which particles vibrate along the direction of the propagation are called longitudinal waves.
19.
In a longitudinal wave, the vibration of particles and the direction of wave are in the same direction.
20.
An example of transverse waves is visible light/Ultraviolet light/x-rays.
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21.
An example of longitudinal waves is sound waves/vibrations in gases/oscillations of spring.
22.
The waves associated with electric and magnetic fields, resulting from the acceleration of an electric charge are called electromagnetic waves.
23.
Electromagnetic waves are transverse waves.
24.
Potential energy is maximum, when the bob is at the position of maximum displacement. Motion which repeats after regular intervals of time is called simple harmonic motion.
25. 26. 27.
Oscillation of pendulum is an example of simple harmonic motion. The maximum displacement of the particle on either side of the equilibrium position is called amplitude.
28.
One complete to and fro motion of the particle about its mean position is called oscillation.
29.
The time taken by the body to complete one oscillation is called time period.
30.
The prongs of
31.
The formula to find the effective length of a simple pendulum is T= 2π
l g
*****
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Chapter 9: Heat Engines 1.
P9
Mention the effects of heat. a) Increase in the temperature of a body. b) Expansion of the body. c) Change of state of matter. d) Chemical change in the body.
2.
Which effect of heat is used in conversion of heat energy into mechanical energy? Change of liquid to gaseous state of matter is most in designing heat engines.
3.
Why cannot increase in temperature and expansion not be used for converting heat energy into mechanical energy? Increase in temperature cannot be used to convert heat energy in to mechanical energy. Expansion of solids, liquids and gases by heat is very small to make it convert into mechanical energy.
4.
What is the principle of working of steam engine? The pressure exerted by the large volume of steam is the basis of working of steam engine.
5.
Explain the principle of working of a diesel or petrol engine. Chemical change of liquid fuels like petrol or diesel when under goes combustion produces large volume of gases and exerts pressure. This is the basis of working of petrol or diesel engine.
6.
Name the two types of movement of air current. Air current has two types of movement: a) Random movement of molecules within the system. b) Enmass laminar flow along the direction of flow.
7.
Why is the Enmass laminar flow along the direction of flow used in the working of heat engines? Enmass laminar flow along the direction of flow results in developing pressure hence it is used in working of heat engines.
8.
What is a heat engine? A heat engine is a device which converts heat energy into mechanical energy.
9.
Name the two types of heat engines. a) External combustion engine b) Internal combustion engine
10.
What is an external combustion engine? Give example. A heat engine in which combustion of fuel takes place outside the cylinder of the engine is called external combustion engine. Ex: Steam engine.
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Briefly explain the working of a steam engine. Description: A steam engine consists of a cylinder fitted with an airtight piston. The piston is connected to a crankshaft by means of a connecting rod. A boiler is connected to the cylinder through the inlet valve. The cylinder is also connected to a condenser through the outlet valve. The condenser is connected to the boiler through a pump. Working: The working of the steam engine is divided into two strokes Expansion stroke: In this stage, the water in the boiler is heated to generate steam of high pressure which is passed into a cylinder fitted with a piston through the inlet valve. As steam occupies larger volume than the same amount of water, it exerts great pressure on the walls of the container in all directions. Steam expands in the cylinder, it pushes the piston forward. Crank shaft connected to the piston also moves. The wheel of the crankshaft makes half rotation during the expansion stroke. Exhaust stroke: After the forward movement of the piston, the steam expands and loses some of its kinetic energy. As a result it condenses into water. The piston is then pushed back into the cylinder due to low pressure region. Due to inertia of the crankshaft, the wheel makes another half rotation and completes one cycle. The condensed water is expelled out through the outlet valve. The cycle repeats and the movement of crankshaft is used for mechanical energy.
12.
Give reason: Steam exerts great pressure on the walls of the piston during expansion stroke. As steam occupies much larger volume than the same amount of water, it exerts great pressure on the walls of the piston.
13.
Give reason: After the expansion stroke of a steam engine, steam condenses into water. As steam expands, it loses its kinetic energy and gets condensed into water.
14.
Give reason: The wheel makes another half rotation after the expansion stroke of steam engine. Due to inertia of the crankshaft, the wheel makes another half rotation and completes one cycle.
15.
Give reason: Use of steam engines for transport vehicles is outdated today. Use of steam engines for transport vehicles is outdated today because they have low efficiency.
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16.
Draw a neat schematic diagram of the expansion stroke of a steam engine.
17.
Draw a neat schematic diagram of the exhaust stroke of a steam engine.
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What are the disadvantages / drawbacks of an external combustion / steam engine? a) Steam engine is bulky and heavy. It cannot be used in small machines. b) The efficiency is very low. c) The engine cannot be started immediately.
19.
Give reason: a) Steam engine cannot be used in small machines. External combustion/steam engines are bulky and heavy hence cannot be fitted into small machines. b) Efficiency of external combustion/steam engine is low. Efficiency of steam engine is low as there is more loss of heat. Most of the heat is lost in boiling of water to increase the temperature of water to its boiling point. c) External combustion/steam engine cannot be started immediately. Heating water to produce steam takes time, so the engine cannot be started instantly. To keep the steam ready fuel must be burnt continuously even if the engine is at rest.
20.
What is an internal combustion engine? A heat engine in which combustion of fuel takes place inside the cylinder of the engine is called internal combustion engine. Ex: Petrol engine, Diesel engine.
21.
Mention the types of internal combustion engine. a) Petro engine b) Diesel engine
22.
Briefly explain the construction of a petrol engine. A petrol engine consists of an air tight piston fitted inside a cylinder. The piston can move smoothly inside the cylinder. The cylinder has two valves – an inlet valve and an outlet valve. It has a spark plug. The piston is connected to a crankshaft. The engine is linked with a carburetor where air and petrol are mixed in proper proportion before letting into the cylinder.
23.
Draw a neat diagram showing the parts of a petrol engine.
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What is meant by stroke of an engine? The motion of piston from one end to another end is called stage/stroke of an engine.
25.
Mention the five stages in the working of a petrol engine. a) Intake stroke
b) Compression stroke
c) Ignition stroke
d) Expansion stroke
e) Exhaust stroke 26.
Briefly explain the working of a petrol engine. In a petrol engine, petrol vapours are mixed with correct amount of air in the carburetor. This mixture is passed into the cylinder a) Intake stroke: In this stroke, the piston moves away from the sparkplug creating a low pressure inside. The inlet valve opens and the fuel-air mixture from the carburetor enters the cylinder. The outlet valve remains closed. b) Compression stroke: In this stroke, both inlet and outlet valve remain closed. The petrol-air mixture is compressed by the piston moving towards the sparkplug. The compression increases the temperature of the mixture but it is not sufficient to ignite petrol. c) Ignition stroke: In this stroke, the compressed petrol-air mixture is ignited by the sparks produced by the spark plug. d) Expansion stroke: In this stroke, the fuel burns quickly producing heat and gaseous products such as carbon dioxide, carbon monoxide and water vapour along with carbon particles. The gaseous products expand suddenly and pushes the piston outwards with a great force. e) Exhaust stroke: In this stroke, the outlet valve opens. Piston moves inside towards the sparkplug. The products of combustion gases are pushed out of the cylinder through the outlet valve.
27.
In the expansion stroke of a petrol engine, the piston is pushed with a great stroke. Why? When the petrol-air mixture is ignited, carbon dioxide, carbon monoxide and water vapour expands suddenly. This exerts a great force on the piston.
28.
How is the initial kinetic energy needed to start the engine? The initial kinetic energy needed to start the engine is provided by the starter motor or kick starter.
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Briefly explain the working of a diesel engine. Construction: A diesel engine consists of an airtight piston fitted inside a cylinder. The piston is free to move inside the cylinder. The cylinder has two valves – an inlet valve and an outlet valve. It has no sparkplug or carburetor as in the case of petrol engine. In place of the spark plug there is an injunction pump. Working: The working of diesel engine consists of five strokes. a) Intake stroke: In this stroke, the piston moves away from the sparkplug creating a low pressure inside. The inlet valve opens and the filtered air enters the cylinder. The outlet valve remains closed. b) Compression stroke: In this stroke, both inlet and outlet valve remain closed. The air is compressed by the piston moving towards the head of the engine. The compression is 4:1 to 25:1. The compression increases the temperature of the air. c) Ignition stroke: In this stroke, a controlled amount of diesel is injected into the cylinder. d) Expansion stroke: In this stroke, Diesel bursts into flame producing heat and gaseous products such as carbon dioxide, carbon monoxide and water vapour along with carbon particles. The gaseous products expand suddenly and pushes the piston outwards with a great force. e) Exhaust stroke: In this stroke, the outlet valve opens. Piston moves inside towards the sparkplug. The products of combustion gases are pushed out of the cylinder through the outlet valve.
30.
Why there is not sparkplug in a diesel engine? The compression of air in the cylinder is 4:1 to 25:1. This compression increases the temperature to around 1000K which is enough to ignite diesel. In the ignition stroke, a required amount of diesel is injected. Hence no sparkplug is needed.
31.
Why is air compressed in a diesel engine? In a diesel engine, filtered air enters the cylinder and gets compressed to generate enough heat to ignite the diesel.
32.
Diesel engines are best suited for heavy vehicles, such as lorries, trucks, railway engines and ships. Why? As they have more power and efficiency of diesel engine is more.
33.
Mention the uses of diesel engine.
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Diesel engines are used a) in transport vehiclesb) in generators to produce electricity d) by some sugarcane juice vendors to crush sugarcane.d) by cement concrete mixers 34.
What is meant by emission test? The test conducted to determine the amount of carbon monoxide emitted by vehicles is called emission test.
35.
List the differences between petrol engine and diesel engine. Petrol Engine 1. Petrol vapour is used as fuel 2. Petrol engines are spark ignition engines. It requires a spark plug. 3. Cost of petrol is comparatively high. 4. Expansion of gaseous products with pressure impulse 5.Efficiency is comparatively less 6. Compression of petrol-air mixture is in the ratio 4:1 to 10:1
36.
Diesel engine 1. Diesel is used as fuel 2. Diesel engine are compression ignition engines. It does not require sparkplug. 3. The cost of diesel is comparatively less 4. Expansion against constant pressure. Efficiency is comparatively more 6. Compression of air is in the ratio 4:1 to 25:1
Define efficiency of a heat engine. The efficiency of a heat engine is defined as the ratio of the actual work done to the heat energy consumed. It is expressed as percentage.
Efficiency =
37.
Write the formula to calculate efficiency.
= η
38.
Actual work done x 100% Heat energy consumed
W x 100 where η (pronounced as Eeta ) Efficiency = H W = workdone by the engine H = Heat energy input
Is it possible to have a heat engine with 100% efficiency? If no why? No, we cannot have a heat engine that is 100% efficient. Whenever heat energy is converted into mechanical energy by a heat engine, a part of the heat energy is lost. Hence we cannot have 100% efficient.
39.
The efficiency of a heat engine is 25%. If 50,000 joules of heat is supplied to the engine. Calculate the useful work done by the engine.
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40.
An engine is designed to convert 40KJ of heat energy into work. If the heat engine consumed by the engine is 60KJ, how high would this engine lift an object of mass one kilogram from the ground?
41.
Calculate the efficiency of an engine which performs work of 400 joules utilizing 1000j of heat energy.
42.
Which of the following is the best engine? a) 720KJ of work done by 1800KJ of heat b) 450KJ of work done by 900KJ of heat c) 100KJ of work done by 1000KJ of heat
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A person develops an engine whose efficiency is 45%. What do you mean by this? An engine is 45% efficient means 45% of the heat supplied is converted into mechanical energy.
44.
An engine is 35% efficient. If 800KJ of heat is consumed by the engine. How much mechanical work is done by it?
45.
Efficiency of a heat engine is 40% and it consumes 900KJ of heat energy. Calculate the mechanical workdone.
46.
An engine is designed to convert 20% of heat energy into work. If the steam in the engine has 80KJ of heat energy, Calculate the useful work done by the engine.
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State the function of the following parts in a heat engine: a) Crank shaft b) spark plug c) carburettord) kick starter e) inlet valve f) outlet valve a) Crankshaft converts the linear movement of piston into circular motion. b) Spark plug is used in petrol engine to ignite the mixture of petrol and air in the cylinder. c) Carburettorhelps to mix petrol vapours and air in proper proportion. d) Kick starter is used to provide the initial kinetic energy needed to start the engine. e) Inlet valve allows the mixture of petrol-air or air into the cylinder. f) Outlet Valve allows the exhaust gases out of the cylinder.
48.
What is the disadvantage of internal combustion engine? Internal combustion engine causes more pollution as it produces exhaust gases like carbon monoxide, carbon dioxide and carbon particles.
49.
What are the advantages of internal combustion engine? a) The efficiency of internal combustion engine is greater then that of external combustion engine. b) It can be started immediately. c) It can be fitted into small machines
50.
Write the meaning of a) unleaded petrol b) antiknock value of petrol c) CNG a) Unleaded petrol means petrol without the lead added to it b) Antiknock value of petrol is c) CNG stands for Compressed Natural Gas. It is a clean fuel. It is environment friendly.
Fill in the blanks: 1.
3.
The effect of heat used in converting heat energy to mechanical energy is change of state of matter. Volume of steam is 700 times more at STP than the volume of water from which it is obtained by heating. The energy transformation in a heat engine is heat into mechanical.
4.
Forward movement of a piston in a steam engine is called expansion stroke.
5.
The basis of working of steam engine is the pressure exerted by the large volume of steam. The basis of diesel/petrol engine is Chemical change of liquid when under goes combustion produces large volume of gases and exerts pressure. The conversion of steam pressure into mechanical energy was known since Roman Empire.
2.
6. 7. 8.
First commercially useful steam engine was constructed by Thomas Savery.
9. 10.
Steam locomotives helped to bring about industrial revolution. In a steam engine, the special shutters used are called valves.
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11. 12.
In a steam engine, the cylinder is connected to the condenser by outlet valve. The fuel used in Raichur Thermal power plant is coal.
13.
In a temporary forest camp, the best way to generate electricity for several hours is to use diesel engine.
14.
Internal combustion engine was invented by Rudolf Diesel and Nikolaus.
15. 16.
The ignition stroke and expansion stroke are together called power stroke. The stroke in which both valves are closed is compression/expansion stroke.
17.
The part of a petrol engine in which petrol vapour and air are mixed is carburetor.
18.
Linear motion of the piston in a heat engine is converted into circular motion by Crankshaft.
19. 20.
The stroke of a heat engine in which outlet value opens isexhaust stroke. Internal combustion engine that does not use spark plug is Diesel engine.
21.
The compression of air in a diesel engine is 4:1 to 25:1.
22.
The part that is not needed in a diesel engine is sparkplug/carburettor.
23.
If an engine is not maintained the production of carbon monoxide increases
24.
The formula to calculate the efficiency of a heat engine is η =
25.
If work done by an engine is equal to the heat supplied, then its efficiency is 100%.
W x 100 H
*****
Girish.N, Bengaluru
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P10
Chapter 10: Nuclear Energy 1.
Why is there a need for nuclear energy? Traditionally used sources of energy like wood, coal and petroleum are not sufficient to meet the ever increasing demand for energy. We need to shift our dependence from nonrenewable to renewable sources of energy. Hence there is a need for nuclear energy.
2.
What are the changes that take place during radioactivity? a) Charged particles energy from neutral atoms. b) An atom gets transmuted into another atom with emission of charged particles.
3.
Which was the first nuclear reaction achieved? The first nuclear reaction was achieved by Ernest Rutherford. 14 7N
+ 2 He4 → 8 O17 + 1H1
4.
What is the main advantage of nuclear reactions?
5.
The main advantage of nuclear reaction is the production of radioactive and nonradioactive isotopes. What is meant by artificial radioactivity? The process of generating radioactive isotopes during nuclear reaction is called artificial radioactivity.
6.
Ex: If aluminium atoms are hit by an alpha particle, we get phosphorous atom which is radioactive. What is meant by transmutation? The process of changing of one element into another element is called transmutation.
7.
Mention the types of nuclear reactions. a) Nuclear fission b) Nuclear fusion
8.
What is meant by nuclear fission? The process of splitting a heavy nucleus into two medium sized nuclei along with release of neutrons is called nuclear fission.
9.
Explain nuclear fission with an example. When uranium 235 atom is bombarded with a slow moving neutron, fission produced a barium atom, a krypton atom, 3 neutrons and a large amount of energy. 235 92 U
Fission + 0 N1 → 56 Ba142 +
36 Kr
91
+ 3 0 n1
10.
What is a chain reaction?
11.
A chain reaction is the process in which number of neutrons keep on multiplying after each fission rapidly in geometric progression, till the whole of the fissionable material is disintegrated. What is a controlled chain reaction? A chain reaction in which the number of neutrons produced is kept constant is called controlled chain reaction.
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How is controlled fission reaction achieved? Nuclear fission reaction produces more than two neutrons. Excess of neutrons are absorbed so that the number of neutrons per fission is regulated to around one neutron per fission.
13.
What is meant by enrichment of uranium? The process of separating
14.
235 and 92 U238 92 U
isotopes is called enrichment of uranium.
What is the need for enrichment of uranium? Naturally occurring uranium contains about 0.7% of 92 U235 isotope which is fissionable. Self stained chain reaction are not possible in natural uranium which is not possible in natural uranium which is mostly made up of isotope 92 U238 .
15.
How is the Graham’s law of diffusion useful in the enrichment of Uranium? Explain. Graham’s law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular mass. This principle is used to separate by passing gaseous uranium through several stages of semi-permeable membrane.
16.
Explain Einstein’s mass energy relation. Albert Einstein derived an equation which is related to the mass transformed into energy and the amount of energy released. 2
The equation is E = mc where E is the energy released in joules, M is the mass transformed in kg 8
C is the velocity of light (3x10 ms
–1
)
17.
Calculate the energy released when one a.m.u of mass is converted into energy.
18.
State the unit of energy released. Joules or electron volt (ev) or million electron volt (Mev) –13
1 Mev = 1.6 x 10
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Define electron volt. One electron volt is the energy gained by the electron when it is accelerated by applying a potential difference of one volt.
20.
What is a nuclear reactor? A nuclear reactor is a device used to carry out fission under controlled condition.
21.
Mention the types of nuclear reactor. a) Breeder reactor [to produce radio isotopes] b) Power reactor [to generate electricity] c) Research reactor [to carry out research programmes related to atomic energy]
22.
Explain the principle of a power reactor. Nuclear reactor is a large reactor in which heat generated by nuclear fission is removed by water and the resulting steam is used to rotate turbine which is connected to a generator.
23.
24.
Name the parts of a nuclear power reactor. a) Nuclear fuel
b) Control rods
e) Coolant
f) Radiation shield
c) Moderator
d) Reflector
Explain the following parts of a nuclear power reactor. a) Nuclear fuel: It is the fissionable material used in a reactor. It is in the form of rods placed in a regular array in a large container. Ex: Enriched uranium 235, Plutonium b) Control rods: They are used to absorb the neutrons. Ex: Cadmium, Boron carbide. c) Moderator: They are used to slow down the neutrons emitted in the fission process. Ex: Heavy water & graphite. d) Reflector: It is used to keep the neutrons confined to the core. Graphite or heavy water can be used as reflector. e) Coolant: It is used to continuously remove the heat released during the fission process. The heat is transferred to a heat exchanger. Ex: Liquid sodium, hydrocarbons with high boiling point, heavy water. f) Radiation shield: It is used to protect the people in the vicinity of the reactor against the harmful effects of nuclear radiations. Ex: Lead g) Heat exchanger: It is used to transfer the heat energy of the coolant to convert water into steam.
25.
What is heavy water? Write its chemical name. Chemically heavy water is deuterium oxide (D 2 O). It is used as a moderator to slowdown the fast neutrons released during fission or as a coolant to remove the heat generated.
26.
When is a nuclear reactor said to be a) shut off b) critical? A nuclear reactor is said to be shutoff when the control rods are inserted sufficiently deep into the core of the reactor.
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A nuclear reactor is said to be critical when the number of fissions per unit time remains constant. 27.
Draw a neat schematic diagram of a nuclear power reactor and label the parts.
28.
Give reason: a) Cadmium rods are used in nuclear reactor.
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Cadmium is a neutron absorber. Hence they are used as control rods to absorb excess neutrons produced during fission reaction. b) A nuclear reactor is enclosed in a concrete building with lead sheets covered inside. To prevent radioactive radiations being released into the environment. c) People working in a nuclear reactor wear lead jackets. Lead can absorb radiations. d) Moderators are not necessary in the IV generation nuclear wave reactors. Slowing down of neutrons is not needed. 29.
Write a note on atomic reactors in India. a) Bhabha Atomic Research Centre [BARC] has been setup for research and development work in atomic energy. b) Tarapur [Maharashtra] atomic power station was the first to be setup in India [1969]. c) Kota [Rajasthan] d) Kalpakam [Tamil Nadu] e) Kaiga [ Karnataka]
30.
What is meant by nuclear fusion? The process by which two or more lighter nuclei combine to form a heavy nucleus with the liberation of large amounts of energy is called nuclear fusion.
31.
Explain nuclear fusion with an example. When deuterium [an isotope of hydrogen] combines with another deuterium nucleus it combines to form helium nucleus with release of energy. 2 1H
32.
Fusion + 1H2 → 2 He4 + energy
What is meant by thermonuclear fusion reaction? The reaction in which fusion of lighter nuclei into heavier nuclei takes place at very high temperatures is called thermonuclear fusion reaction. Energy produced by stars and sun are due to thermonuclear fusion reactions.
33.
Mention the differences between nuclear fission and nuclear fusion. Nuclear Fission
Nuclear Fusion
1. A heavy nucleus splits into two lighter nuclei with liberation of energy
1. Two or more lighter nuclei fuse to form a heavy nucleus with liberation of energy.
2. It can be controlled.
2. At present there is no mechanism to control fusion reactions
3. It does not require high temperature.
3. It requires very high temperature 6 (10 K)
4. It causes radiation pollution due to radioactive products
4. It does not cause radiation pollution since the products are not radio active.
5. The energy produced is less than that of fusion.
5. The energy produced is much more than that of fission.
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6. Uncontrolled fission results in an atom bomb. 34.
99
6. Uncontrolled fusion results in hydrogen bomb.
What are the hazards of nuclear materials? a) Ionising radiations like gamma rays can cause mutation in the living cells. b) It can cause DNA alterations. c) Certain types of cancer and hereditary disorder are caused by ionizing radiations.
35.
Give reason: Radioactive material of longer half life is dangerous. Since the radioactivity lasts longer.
36.
Environmentalists oppose setting up nuclear power plants. List four arguments to support this. a) Fear of radioactive gases. b) Fear of destruction of large number of evergreen trees of Western Ghats. c) Health hazards of radioactive radiations. d) Nuclear wastes can cause soil pollution, water pollution.
37.
How can nuclear wastes/ radioactive wastes disposed? Radioactive matter is impregnated in glass slab and disposed in the deep sea in strong steel containers so that radiation cannot reach the level of biosphere.
38.
Nuclear disarmament is a need in today’s situation. Support this statement. Production of dangerous weapons like atom bomb cause large scale destruction. Increased production of nuclear weapons has brought the world to the brink of a major war. Such weapons can also fall into hands of terrorists. Hence the need of today’s world is nuclear disarmament.
39.
Mention the differences between chemical reactions and nuclear reactions. Chemical reactions
Nuclear reactions
1. Valence electrons of the atoms take part in the reaction
1. Electrons of an atom do not take part in nuclear reaction
2. Nucleus of an atom does not undergo any change
2. Nucleus of the atoms undergo a change
3. Products are predictable.
3. Products depend upon conditions
4. Mass conserved
4. A small amount of mass is converted into energy
5. Inter conversion of compounds to elements or elements to compounds take place
5 Production of new elements and isotopes take place.
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Fill in the blanks: 1. 2. 3.
Radioactivity is a nuclear phenomenon. Nuclear reaction is a chance reaction. The process of generating radioactive isotopes during nuclear reaction is called artificial radioactivity.
4.
The process of splitting a heavy nucleus into two medium sized nuclei along with release of neutrons is called nuclear fission.
5.
A chain reaction in which the number of neutrons produced is kept constant is called controlled chain reaction.
6.
The principle of a nuclear reactor is controlled chain reaction.
7.
Controlled chain reaction is the working principle of nuclear reactor.
8.
The process of separating
9. 10. 11.
The principle of enrichment of uranium is Graham’s law of diffusion. 1 a.m.u = 931 Mev. Einstein’s mass energy equation is E = mc2.
12.
The device used to carry out fission under controlled condition is called nuclear reactor.
13.
Breeder reactor is used to produce radio isotopes.
14. 15. 16.
Power reactor is used to generate electricity. An example of nuclear fuel is enriched uranium 235 / plutonium. An example of control rod is cadmium / boron carbide.
17. 18.
An example of moderator is Heavy water / graphite. The chemical formula of heavy water is D 2 O.
19.
The ratio of number of ordinary water molecules to that of heavy water molecules is 1:6000.
20.
An example of coolant is liquid sodium /hydrocarbon/ heavy water.
21.
The part of the nuclear reactor that controls the speed of neutrons released during nuclear fission is moderator.
22.
The speed of neutrons in a nuclear reactor is reduced with the help of graphite / heavy water.
23.
The metal cover used in the walls of nuclear reactor to prevent radioactive radiations being released to the environment is lead.
24. 25.
A nuclear reactor has to be shutdown, the rods used for this purpose is made of cadmium / boron carbide. In modern reactors there is no need for moderator.
26.
The first atomic power station in India was started at Tarapur [Maharashtra].
27. 28.
India’s uranium supply comes mainly from Juduguda mines in Bihar. Fusion reactions which take place at very high temperature are called thermonuclear fusion reactions.
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235 and 92 U238 92 U
is called enrichment of uranium.
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101
Chapter 11: Industrial Inorganic Chemistry
C11
(A) Glass 1. What is glass? Glass is chemically sodium and calcium silicate. 2.
Why is glass referred to as ‘Super Cooled liquid’? The molecules of glass are arranged as in that of a liquid. On heating, glass first becomes soft and flows like a liquid. It does not have a definite melting point. Hence glass is referred to as super cooled liquid.
3.
Name the raw materials required for the manufacture of glass. a) Soda Ash (Na 2 CO 3 ) b) Lime stone (CaCO 3 ) c) Sand (SiO 2 ) d) Broken pieces of glass (Cullets)
4.
Why are broken glass pieces or cullets added during the manufacture of glass? Pieces of broken glass are added to increase fusibility and to recycle broken glass pieces.
5.
Mention the steps involved in the manufacture of glass. a) Melting
6.
b) Shaping
c) Annealing
d) Finishing
Briefly explain how glass is manufactured. The raw materials used in the manufacture of glass are soda ash, lime stone, sand and cullets (broken glass pieces). The raw materials in proper proportion are finely powdered and mixed. This mixture is fused by heating it in a furnace at high temperature (about 2073K). The charge melts and following reactions take place.
→ CaSiO 3 + CO 2 ↑ CaCO 3 + SiO 2 → Na 2 SiO 3 + CO 2 ↑ Na 2 CO 3 + SiO 2 When all the carbon dioxide escapes out of the molten mass, decolourizers such as manganese dioxide is added to remove the ferrous compounds and carbon. 7.
What is the role of the following in the manufacture of glass? a) Cullets b) Manganese dioxide a) Cullets are added to increase the fusibility. b) Manganese dioxide is added to decolourise & remove ferrous compounds and carbon.
8.
How is molten glass shaped? Molten glass is made into desired shapes by either blowing or moulding or pressing between rollers.
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What is meant by annealing of glass? Explain The process of gradual cooling of glass articles to room temperature is called annealing. Glass articles are allowed to cool gradually to room temperature by passing through different chambers with decreasing temperature.
10.
What is the purpose of annealing? If glass is not cooled slowly, it becomes brittle and breaks easily. On slow cooling, glass can withstand stress and lose brittleness.
11.
Why should glass articles be annealed? If glass articles are allowed to cool rapidly, glass being bad conductor of heat, the superficial layer cools down first leaving the interior portion in a state of strain. Due to this unequal expansion, the articles are likely to crack into pieces.
12.
How are the air bubbles in glass removed? Air bubbles in glass are removed by adding borax or aluminium powder to the glass and heating slowly. The air bubbles escape from glass in the process. Aluminium powder / borax settle at the bottom, which can be removed easily.
13.
What is the role of borax or aluminium powder in the manufacture of glass? The function of borax / aluminium powder is to remove the air bubbles in glass.
14.
Give reason: Glass objects when held to flame acquires golden yellow colour. The sodium content of sodium silicate present in glass makes the flame to acquire golden yellow colour to the flame.
15.
Mention the properties of glass. a) Glass is chemical resistant. Glass container can hold aquaregia. b) It has smooth and shining surface. It can be polished. c) It can be moulded into different shapes. d) It can be coloured. e) It is transparent. f) It can be sketched to produce designs. g) Properties of glass can be altered suitably by including additives.
16.
h) Transparent nature of glass can be made automatically adjustable to the intensity of light. What is aquaregia?
17.
Aquaregia is a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio 3:1 Why is glass a cheap substance?
18.
The raw materials used in manufacture of glass are cheap and available in most of the geographical areas. It does not require sophisticated technology to manufacture. What happens when a piece of bangle is heated in a candle flame? When a piece of bangle is heated in a candle flame, it first becomes soft and then melts as glass does not have a definite melting point.
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Why does glass crack when suddenly heated or cooled? Glass is a bad conductor of heat but expands easily on heating. When it is suddenly heated or cooled, due to rapid expansion and contraction along the hot region and cold region it begins to crack.
20.
What are the limitations of glass? Glass is brittle and dense. Glass gets scratched which is difficult to remove.
21.
What is the advantage of synthetic polymer over glass? OR Why is glass being replaced by synthetic polymers? Glass is being replaced by light and transparent synthetic polymers like poly methyl metacrylate polymers. The advantages of polymers are that they are unbreakable, light and scratches on polymers can be removed by wiping with acetone.
22.
Give reason: Glass bottle immersed in a vessel filled with water does not break even when water beings to boil. Glass is a bad conductor of heat.
23.
Give reason: When a glass test tube containing a mixture of chloroform and acetone is immersed in water will disappear. The mixture of acetone and chloroform has the same refractive index as that of the glass. The surface of glass will not reflect light. Hence the test tube appears to disappear.
24.
How is coloured glass prepared? Soda-lime glass is colourless. To make coloured glass, certain metal compounds are added.
25.
Metallic compound
Colour imparted
Ferric compound
Yellow
Ferrous & Chromium compound
Green
Cobalt compound
Blue
Nickel salts or cuprous compounds
Red
Give reason: Broken edges of glass have a slight greenish tinge. Common sand used in the manufacture of glass contains some amount of iron salts. Iron salts give green colour to the glass.
26.
Mention the different types of glass. a) Soda-lime glass. b) Potash-lime or Bohemian glass. c) Lead glass or flint glass. d) Borosilicate glass / Pyrex glass / Jena glass. e) Safety glass.
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C11: Industrial Inorganic Chemistry
Mention the properties and uses of different types of glass. No.
Type of glass
Additive added
Property
Uses Window glass, electric bulb, plate glass, bottles, jars, Cheaper table ware
1
Soda-lime
-
Low cost, resistant to water melts easily
2
Potash-lime or Bohemian glass
Silica, calcium carbonate & potassium carbonate
High melting point, fuses with difficulty
Manufacture of chemical apparatus, combustion tubes
3
Lead or flint glass
Lead oxide
-
Manufacture of lenses, neon sign tubings, cathode ray tubes
4
Borosilicate or Pyrex or Jena glass
Silica and boron with small amounts of alumina
-
Preparation of pipelines, superior laboratory apparatus
Safety glass
Sandwiching thin layer of synthetic vinyl plastic in between two glass sheets
Does not form sharp edges when broken
Windshield of automobiles and aeroplanes
5
28.
What property of safety glass is made use in manufacture of windshield of automobiles? Safety glass does not form sharp edges when broken. This property is used in manufacture of windshields of automobiles and aeroplanes.
29.
What is optical fibre? Optical fibre is a flexible, transparent fibre made up of very pure glass.
30.
Mention the uses of optical fibres. Optical fibres are used as a medium for telecommunication and networking.
31.
Why are optical fibres used in telecommunication and networking?
32.
Optical fibres are flexible and can be bundled as cables hence it is used in telecommunication and networking. What is photonics? Communication using photon and optic fibres is known as photonics.
33.
105
What are the merits / advantages of optical fibres? a) Optic fibres do not interact with air or water, so it does not corrode. b) Messages reach the destination much faster as photons transmit much faster than electrons. c) Optic fibres can transmit more messages at once, compared to transmission by electrons in a wire.
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Give reasons: a) Optic fibres do not corrode. As optic fibres do not react with air or water b) Messages in optic fibres reach faster. As photons travel much faster than electrons.
(B) Ceramics 35.
What is ceramics? The products that are prepared out of specific mud are called ceramics.
36.
What are the raw materials used in the manufacture of ceramics? Clay like kaolinite and bentonite, Flint, White clay, Quartz and feldspar.
37.
What is clay? Mention its properties. Clay is complex mixture of silicates. It is a naturally occurring thermally setting substance. Clay can be moulded to any desired shape. It becomes hard and brittle on heating but it retains it shape.
38.
Briefly explain how ceramic products are prepared. The raw materials used in the manufacture of ceramics are clay, feldspar. Clay is mixed with required quantity of water. Desired shape is given to the mixture. Then the products are heated in a kiln. This partially eliminates water.
39.
How are the pores in ceramic articles plugged? The pores in the baked ceramic articles are plugged by a process of glazing.
40.
What is glazing of ceramics? The process of making the clay products into non-porous shining material is called Glazing.
41.
Explain glazing of ceramic articles. Glazing is achieved by addition of suitable fillers. It is fired again to create coloured, smooth surface.
42.
What are the merits / advantages of glazing ceramic articles? a) Glazing plugs the pores present in the baked ceramic articles. b) Glazing provides a smooth, attractive look and bright glossy surface to the articles. c) Glazing provides desired colour to the articles.
43.
What are the characteristics of ceramic articles? Ceramic articles are brittle, porous, heat resistant (withstand high temperature) and noncorrosive to chemicals.
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44.
Give reason: Unglazed ceramic materials are used in water filters.
45.
Unglazed ceramic materials use the small pores to filter dirt, debris and bacteria out of water. How can cracking of ceramic articles be controlled?
107
Cracking of ceramic articles can be controlled if non-clay materials like flint and quartz are added to the mixture. 46.
47.
Why addition of flint and quartz to molten glass does not shrink or get transformed? Flint and quartz are forms of silica, they do not absorb water. As water is not absorbed, they do not get transformed on heating and do not shrink. What is the role of feldspar in the manufacture of glass? When feldspar is added, glass will have a smoother glossy finish. It also adds strength to the ceramic articles.
48.
What is the characteristic of all ceramics manufacture? Shaping – drying – firing is the characteristic of all ceramic manufacture.
49.
What is the effect of heating ceramic articles during manufacture? On heating ceramic materials to about 1073K to 1273K, they melt into a glass like liquid, which fills the pores between individual clay particles and strengthens their contact points. On cooling, the material becomes glossy and has shining & smooth finish.
50.
Give reason: Water kept in porcelain container will not get cooled if it is glazed. Glazing plugs the pores present in porcelain articles. If pores are present, water oozes from these pores and gets evaporated. This has a cooling effect on the water inside, As the pores are plugged, water does not get evaporated hence no cooling.
51.
Give reason: Water in an earthen pot will become cooler. An earthen pot has a number of pores. Water oozes out of the pores and gets evaporated. This has a cooling effect on the water inside.
52.
Two small identical earthen pots A and B are taken. Paint is smeared thoroughly on pot A. Equal quantity of water is filled in both pots till the brim. In which pot the water will be cold? Why? In pot B water will be colder than that of pot A. In pot A, paint is smeared. The pores are closed. So water drops cannot evaporate through the walls. In pot B which is unpainted water evaporates and has cooling effect on the water inside.
53.
Give reason: Pickle is stored in ceramic jars but not in earthen pots. Pickles contain oil and salt. If they are stored in earthen jars (without glazing), oil will ooze out of the pores and start leaking. In ceramic jars with glazing, oil will not leak so pickles are stored in ceramic jars.
54.
Give reason: Lemon juice kept in metallic cup will taste different but not in ceramic cup.
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Lemon juice contains citric acid which reacts with metallic cup and makes it toxic. So it tastes different. Ceramic cup does not react with acid.
55.
Mention the uses of ceramics. a) Ceramics are used as insulators (like fuse, sparkplugs etc). b) They are used to replace steel in ball bearings. c) They are used in spare parts for gas turbine engines. d) They are used in dental implants and synthetic bones. e) They are used in storing pickles f) They are used to keep water cold. g) They are used in storing chemicals in chemical laboratory. h) They can be used as substitutes to replace plastic cups. i)
56.
They are used in musical instruments like Ghatam, Jalatarang etc.
Write one similar character between glass and ceramics. Glass and ceramic melt at 1073K and both are brittle.
57.
Mention the advantage of the following raw material in ceramics. Sl. Additive No 1
Clay
Porous, desired shape, becomes hard on heating
2
Flint
Cracking can be controlled as it does not absorb water
3
Quartz
Cracking can be controlled as it does not absorb water
4 58.
Advantage
Feldspar Gives smoother, glossy finish. It also adds strength
Give reason why the following are used. Sl. No
Use of ceramics
Reason
1
Floor vitrified tiles
Water proof, smooth, glossy finish. Available in different colours
2
Part of electric gadgetry Non-conductor
3
Pickle jar
Non-porous, does not corrode
(C) Paper 59.
How is paper prepared? Paper is produced by pressing together moist fibres (cellulose pulp) derived from wood, rags or grasses and drying them into flexible sheets.
60.
Mention the steps involved in the manufacture of paper. a) Pulping
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b) Mixing additives
c) Drying
d) Finishing
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What is meant by pulping of paper? Pulping is the process where wood is chipped and made into fibres.
62.
How can the characteristics of paper for printing or writing be improved? Fibres, pulp obtained from wood can be mixed with additives like chalk or china clay to improve the characteristics of paper.
63.
Explain drying step in the manufacture of paper. After obtaining paper web, water is removed from it be using air or heat. Earlier method of drying was to hang paper sheets as clothes. Now steam heated can drier are used for drying paper.
64.
Briefly explain the manufacture of paper. First wood is chipped into pieces and made into fibres. The moist fibres are pressed together. Additives like chalk or china clay may be added to improve the characteristics of paper. Then the pulp is fed into a paper machine where it forms a paper web. Water form the paper web is removed by hanging or by using steam heated can drier. Now the paper is cut into different sizes to alter its physical properties.
65.
How is coated paper formed? After normal paper is obtained. a thin coat of calcium carbonate or china clay is applied to get coated paper.
66.
Strips of newspaper, filter paper and glazed paper are dipped in dilute potassium permanganate solution. Which paper will have absorbed more potassium permanganate? The level of potassium permanganates in filter paper will be maximum as is more porous.
67.
Why do we find increased porosity, yellowish tinge and lack of tensile strength in old paper? Paper contains significant amount of lignin. Exposure of lignin to air and sunlight causes old paper to turn yellowish.
68.
How can important documents be protected from turning yellow? Paper can be laminated to avoiding fading of printed matter due to air, moisture and radiations. A thin sheet of polythene is placed on the document to be protected and it is gently heated to melt the polythene followed by solidification.
69.
Mention the different types of paper. a) Filter paper b) Tissue paper c) Wax paper
70.
d) Cardboard paper What are the characteristics and uses of filter paper?
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Filter paper is a semi-permeable paper. It is porous in nature. Uses: a) It is used to separate fine solids from liquid or air. b) It is used in chemical laboratory with filter funnel. c) Filter paper smeared with various reagents is used in pH paper. 71.
d) It is used in dip tea bags. What are the characteristics and used of tissue paper? Tissue paper is very light. It can be made from virgin or recycled paper. Tissue paper is used as facial tissue napkins and house hold towels.
72.
What are the characteristics and used of wax paper? Wax / paraffin paper is moisture proof. It is made by applying wax which makes it non porous. It is used in wrapping food for storage such as cookies, ice creams etc. It is also used in arts and crafts.
73.
Give reason: Wax paper is used in storing cookies and ice-creams. Wax paper makes it non-porous and keeps the contents moisture resistant. Hence wax or paraffin paper is used in storing cookies, ice-creams etc.
74.
How is cardboard paper prepared? Cardboard paper has more tensile strength. This is achieved by having multi layer. It is used in post card, posters and drawing board.
75.
Why does paper becomes translucent when smeared with oil? When oil is smeared on paper, more light is transmitted through oil and less light is reflected. Hence it becomes translucent.
76.
Mention the limitations of paper. a) Paper is not perfectly non-porous. b) The tensile strength reduced on wetting.
77.
Write about the future of paper. New, eco-friendly, biodegradable alternatives are being developed to expanded plastic packaging made out of paper. Synthetic materials have been introduced as printing media as more durable material than paper. Paper bags can replace plastic bags as they are eco-friendly.
78.
Give reason: It is easy to tear wet paper than dry paper. The tensile strength of paper decreases when paper becomes wet.
79.
Why is paper considered as eco-friendly substance?
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Paper is biodegradable because it can be recycled and also it gets converted into simpler substance by microorganisms. 80.
List the uses of paper. a) Paper is used in making cups, bags, packing materials, stationary. b) It is used in Origami / Kirigami. c) It is used as filter paper in chemical laboratory to separate fine solid particles from liquids. d) It is used in dip teas bags. e) It is used in facial tissue napkins and house hold napkins. f) It is used in wrapping food for storage such as cookies, ice-creams etc. g) It is used in making post cards, posters, and display boards.
81.
h) It is used in pH papers. i) It is also used in arts and crafts. Give reason: Paper absorbs water/oil. Since paper is porous, it absorbs water and oil.
Fill in the blanks: 1. Chemically glass is a mixture of sodium and calcium silicate. 2. 3.
Mixture of sodium silicate and calcium silicate is called glass. Glass is referred to as super cooled liquid.
4.
Glass is transparent to visible light but opaque to infra-red light.
5. 6.
The raw materials used in glass manufacture are soda ash, lime stone and sand. To increase fusibility of glass pieces of broken glass are added.
7. 8. 9.
During manufacture of glass, cullets are used to increase the fusibility. The gaseous product released during the manufacture of soda glass is carbon dioxide. The substance added to decolourise the glass articles during manufacture of glass is Manganese dioxide.
10.
The process of gradual cooling of glass articles to room temperature is called annealing.
11. 12.
During manufacture of glass, molten glass is cooled slowly to make it lose brittleness. The function of borax / aluminium powder is to remove the air bubbles in glass.
13.
The mixture of concentrated hydrochloric acid and concentrated nitric acid is called Aquaregia.
14.
Aquaregia is a mixture of HCl and HNO 3 in the ratio 3:1.
15. 16.
Soda lime glass is colourless. Yellow coloured glass is prepared by adding ferric compounds.
17. 18.
Green coloured glass is prepared by adding ferrous or chromium compounds. Blue coloured glass is prepared by adding cobalt compounds.
19.
Red coloured glass is prepared by adding nickel or cuprous compounds.
20.
A person wants to use a glass vessel in his microwave oven. The type of glass that can be used is borosilicate glass.
21.
The type of glass used in making electric bulbs is soda-lime glass.
22.
The type of glass used in making bottles is soda-lime glass.
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23. 24.
The type of glass used in making chemical apparatus is potash-lime/Bohemian glass. The type of glass used in making combustion tubes is potash-lime / Bohemian glass.
25.
The type of glass used in making lenses is lead glass.
26.
You have to prepare a prism to disperse light to get spectrum. The glass used is lead glass.
27. 28.
The type of glass used in making neon sign tubings is lead glass. The type of glass preferred to make superior laboratory apparatus is borosilicate / Pyrex / Jena glass.
29.
The type of glass used in making windshields of automobiles is safety glass.
30. 31. 32.
Communication using photon and optic fibre is known as photonics. Materials prepared out of specific mud are called ceramic. The process of making clay products non-porous and shining is called glazing.
33.
The word ‘ceramics’ is derived from the Greek word ‘Keramos’. Meaning burnt earth.
34.
Cracking of ceramic articles can be controlled by non-clay materials like flint/quartz.
35. 36.
The material added to ceramics to add strength is feldspar. The characteristic of ceramics is shaping-drying-firing.
37.
Ceramic articles melt into liquid at a temperature of about 1073 to 1273K.
38. 39. 40.
Water kept in porcelain contains do not become cold due to the absence of holes. A material that can be safely be used in making fuse box is porcelain. A musical instrument that is made of ceramic material is Ghatam / Jalatarang.
41. 42.
The word paper is derived from papyrus. The process of chipping wood and making into fibres is called pulping.
43.
The substance added to improve the characteristics of writing paper is chalk or china clay.
44. 45. 46.
The substance used in coating paper is calcium carbonate or china clay. The type of paper used in dip tea bags is filter paper. They type of paper used in wrapping cookies or ice-cream is wax or paraffin paper.
47. 48.
Wax paper is also known as paraffin paper. The major natural polymer present in paper is Cellulose.
49.
The coating chemical used to coat paper in the final stage of manufacturing paper is Calcium carbonate or china clay.
50.
Paper turns yellowish with age due to the presence of the chemical lignin. *****
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Chapter 12: Carbon & its compounds
C12
(A) Carbon 1.
Mention the properties of carbon. Carbon is a non-metal It is the first member of group 14 of periodic table. Its valency is four.
2.
What happens when? a) A little sugar is heated in a spatula It turns black indicating that it contains carbon. b) Chapati or roti is over heated. It turns black indicating the presence of carbon. c) A small quantity of milk is continuously boiled. It gets charred indicating the presence of carbon in it. d) A small quantity of sand is heated. It gets hot but not black indicating the absence of carbon.
3.
Why are carbon-based compounds lumped together as a separate subject within the study of chemistry? Carbon is a unique element. It is the king of versatility. Its ability to connect with other carbon atoms through strong and stable covalent bonds sets it apart from other elements. Carbon forms an exceptionally large number of compounds because of its unique characteristics like catenation, tetravalency and isomerism. Therefore carbon-based compounds lumped together as a separate subject within the study of chemistry.
4.
Will carbon as an atom interact with other atoms to form ionic or covalent bonds?
5.
Carbon as an atom interacts with other atoms to from covalent bonds. What is allotropy? Allotropy is the property of elements which have same chemical properties but different physical properties.
6.
Name the allotropic forms of carbon Crystalline carbon – Diamond & graphite Amorphous carbon
7.
8.
Why is diamond hard whereas graphite soft even through both are crystalline forms of carbon? The reason for difference is because of arrangement of carbon atoms. Mention the uses of graphite. a) Graphite is used as lead in pencils. b) It is used as a pigment. c) It is used as a moulding material in glass manufacture. d) It is used as electrode in batteries, electroplating and electroforming. e) It is used in brushes of electric motors f) It is used as a neutron moderator in nuclear reactors.
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Why is carbon a unique element? Carbon is the king of versatility. It has the ability to connect with other carbon atoms through strong and stable covalent bonds.
10.
How is carbon able to form large number of compounds? Carbon is able to form thousands of compounds because of its unique characteristics like catenation, tetravalency and isomerism.
11.
What are the two properties of carbon which lead to the formation of a large number of carbon compounds? Catenation and isomerism
12.
What is meant by catenation? The unique ability of carbon to form bonds with other atoms of carbon is called catenation.
13.
Mention the type of chain formed by carbon. a) Straight chain b) Branched chain c) Closed chain
14.
Why cannot thousands of compounds of Boron or silicon or germanium not possible? Even though B-B, Si-Si, Ge-Ge bonds exits, these compounds are unstable and very reactive and do not last long.
15.
Write the electronic configuration of carbon atom when it is in ground state. The electronic configuration of carbon atom in ground state is 1s2, 2s2, 2p2
16.
Write the excited state electronic configuration of carbon atom. 2
1
1
1
1
1s , 2s 2px 2py 2pz 17.
Why is carbon tetravalent? Carbon has four electrons in its outermost orbit, so its valency is four. 2 2 2 The electronic configuration of carbon is 1s , 2s , 2p
It has 2 paired and 2 unpaired electrons. On excitation, one electron from 2s level is promoted to 2p level thus there will be four unpaired electrons. Hence carbon is tetravalent. 18.
What is isomerism? The phenomenon in which organic compounds have same molecular formula with different structural arrangement of atoms in them is known as isomerism.
19.
What are the properties of isomers? a) Isomers have same molecular formula. b) They have different structural arrangement.
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21.
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c) They have different physical and chemical properties. What do you call the compounds having the same molecular formula but different structural arrangements of atoms? Isomers Name some elements which exhibit isomerism. Butane, Pentane
22.
Why do first three alkanes methane, ethane and propane have no isomers? Methane (CH 4 ), ethane (C 2 H 6 ) and propane (C 3 H 8 ) have no scope for branching of C – C chain hence they do not exhibit isomerism.
23.
Write the isomers of butane. Molecular formula of Butane is C 4 H 10 . It has two isomers n-Butane and Iso-butane.
n-butane 24.
Iso-butane
Write the isomers of pentane (C 5 H12 ).
n-pentane
Iso-pentane
Neo-pentane
25.
What is the vital force theory?
26.
In 1827 Berzelius put forward the vital force theory to account for the formation of organic compounds. According to this theory – Organic compounds were synthesized in living systems under the influence of a vital force. Which was the first organic compound to be prepared? In 1828 Friedrich Wohler prepared urea, a typical product of animal metabolism by heating an aqueous solution of an inorganic compound ammonium cyanate which is obtained from non-living material.
27.
Organic compounds are formed under some vital force. True or false. Explain. Organic compounds are not formed under vital force is false because earlier they thought that organic compounds could not be prepared in the laboratory. In 1828 Friedrich Wohler prepared urea, a typical product of animal metabolism by heating an aqueous solution of
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an inorganic compound ammonium cyanate which is obtained from non-living material. This disproved that organic compounds are formed under some vital force. 28.
Which events disproved the vital force theory of Berzelius? OR Why was vital force theory rejected? The synthesis of urea by Friedrich Wohler, acetic acid by Kolbe and methane by Berthellot disproved the vital force theory.
29.
Why are Calcium Carbide (CaC 2 ), Carbon monoxide (CO), Carbon dioxide (CO 2 ), Hydrogen cyanide (HCN) and calcium carbonate (CaCO 3 ) classified as inorganic compounds through they contain carbon? These compounds contain only one or two carbon atoms per formula unit and contain no carbon-carbon (C-C) bonds or carbon-hydrogen bonds. Hence they are classified as inorganic compounds.
30.
Who suggested the classification of chemical compounds as inorganic and organic? J.J.Berzelius
31.
Mention the differences between organic and inorganic compounds.
Sl. No
2
Melting & Boiling points Nature of bonding
3
Solubility
4 5
Combustibility Nature of reaction Homology & Isomerism
1
6 32.
Property
Organic compounds Low, generally volatile covalent insoluble in water, soluble in organic solvents almost all burn slower & molecular
Inorganic compounds High, generally nonvolatile ionic soluble in water, insoluble in organic solvents very few burn very fast reactions
is common
is not common
What is organic chemistry? Organic chemistry is the study of compounds and reactions involving carbon. OR It is the study of chemistry of carbon compounds of both natural and synthetic origin.
33.
Name three typical organic compounds commonly present in our food. Starch, sugar, citric acid, cooking oil etc.
34.
Write a note on the significance of organic chemistry. Organic chemistry is used in biochemistry especially in the pharmaceutical industry and petro-chemistry. It is used as dyes, flavours, detergents, perfumes, cosmetics.
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(B) Hydrocarbons 35.
What are hydrocarbons? Hydrocarbons are the simplest binary organic compounds containing carbon and hydrogen.
36.
Why are hydrocarbons currently the main source of world’s electrical energy and heat source? The energy produced when burnt often this energy is used directly as heat as in home heaters which use either oil or natural gas.
37.
On the basis of structure, how are hydrocarbons classified? Based on the structure, hydrocarbons are classified into: a) Open chain or acyclic compounds. b) Closed chain or cyclic or ring compounds.
38.
What are aliphatic or acyclic or open chain hydrocarbons? The hydrocarbons which consist of straight or branched chains of carbon atoms are called aliphatic or acyclic hydrocarbons.
39.
How are aliphatic hydrocarbons classified? Aliphatic hydrocarbons are classified into saturated and unsaturated hydrocarbons.
40.
What are saturated hydrocarbons? Aliphatic hydrocarbons are the simplest hydrocarbons which have single bond between carbon atoms.
41.
What are alkanes?
42.
Alkanes are saturated hydrocarbons in which the carbon atoms are connected by only single bond. Ex: Methane, Ethane, Propane Give reason: Ethane is a saturated hydrocarbon.
43.
Ethane is said to be saturated hydrocarbon since each molecule has no carbon-to-carbon double bond and has the maximum possible number of hydrogen atoms. Mention the characteristics of alkanes. a) In alkanes the carbon atoms are bonded with maximum number of hydrogen atoms. b) They have single bond between carbon atoms. c) Their general formula is C n H 2n+2
44.
d) The primary suffix of these hydrocarbons is ‘ane’. Why are alkanes referred to as paraffins?
45.
Paraffin is derived from the Latin word meaning ‘less activity’. Alkanes are compounds which undergo few reactions. Hence they are referred to as paraffins. Why is methane referred to as ‘marsh gas’?
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Methane is formed in marshy places by bacterial decomposition of the vegetable matter. Hence it is called marsh gas. 46.
Give reason: Alkanes are chemically stable. In alkanes all carbon atoms are bonded to the maximum number of hydrogen atoms. They are made up single bond between carbon atoms and are saturated with hydrogen in every bond is used. Hence they are chemically stable.
47.
Write the molecular formulae of the third and fifth member of homologous series of carbon compounds represented by the general formula C n H 2n+2 Third member n = 3, C 3 H 2x3+2 = C 3 H 8 Fifth member n = 5, C 5 H 2x5+2 = C 5 H 12
48.
What does IUPAC represent? IUPAC stands for International Union of Pure and Applied Chemistry.
49.
Briefly explain the structure of methane. The molecular formula of methane is CH4. It is the first member of alkanes or the saturated hydrocarbons. In methane, each carbon is bonded to four other atoms through single covalent bond. The following is the structure of methane.
50.
Explain the laboratory method of preparation of Methane. A mixture of sodium acetate and soda lime (NaOH + CaO) is heated in a hard glass test tube and methane gas is evolved. It is collected by the downward displacement of water. CaO CH 3 COONA + NaOH → Na 2 CO 3 + CH 4
51.
Draw a neat diagram of the laboratory manufacture of methane.
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52.
Why is methane gas collected by the downward displacement of water?
53.
Methane gas is collected by the downward displacement of water because it is insoluble in water. Mention the physical properties of methane. a) Methane is colourless, odourless gas. b) It is lighter than air. c) It is slightly soluble in water and favourable soluble in organic solvents like alcohol and ether.
54.
Mention the chemical properties. a) Methane being saturated is chemically inert. b) It is not attacked acids, alkalies and oxidising agents like concentrated sulphuric acid, nitric acid and potassium permanganate.
55.
What happens when: a) When a mixture of sodium acetate and soda lime is heated in a hard glass test tube. Methane gas is evolved. CaO CH 3 COONA + NaOH → Na 2 CO 3 + CH 4
b) Methane is burnt in air or oxygen or methane undergoes complete combustion. It forms carbon dioxide and water.
→ CO 2 + H 2 O CH 4 + 2O 2 c) Methane gas burns with yellow flame or methane undergoes incomplete combustion. It forms carbon monoxide and water.
→ 2CO + 4H 2 O 2CH 4 + 3O 2 d) A mixture of methane and chlorine is exposed to ultraviolet light (sunlight). Organic product chloromethane is formed
→ CH 3 Cl + HCl CH 4 + Cl 2 UV
56.
Write about the combustibility of methane. a) Complete combustion: During complete combustion methane burns in air or oxygen with a non-luminous flame, forming carbon dioxide and water.
→ CO 2 + H 2 O CH 4 + 2O 2 b) Incomplete combustion: During incomplete combustion, methane gas burns with yellow flame, carbon particles are seen. Methane + Oxygen → Carbon monoxide + Water
→ 2CO + 4H 2 O 2CH 4 + 3O 2 57.
Complete and balance the following equation:
→ a) CH 4 + O 2 → b) CH 4 + Cl 2 UV
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State two disadvantages of incomplete combustion. Incomplete combustion leads to unburnt carbon in the form of soot which pollutes the atmosphere, blackens cooking utensils.
59.
It leads to the formation of extremely poisonous gas called carbon monodioxide. What is meant by substitution reaction? The reaction in which one or more hydrogen atoms of a hydrocarbon are replaced by some other atoms is called substitution reaction.
60.
Name the product obtained when methane and chlorine is exposed to ultraviolet light (sunlight). When a mixture of methane and chlorine is exposed to ultraviolet light, chloromethane is formed.
→ CH 3 Cl + HCl CH 4 + Cl 2 UV
61.
How is dichloromethane formed? When two hydrogen atoms of a methane molecule is replaced by chlorine, dichloromethane is formed.
→ CH 2 Cl 2 + HCl CH 3 Cl + Cl 2 UV
62.
How is trichloromethane formed? When three hydrogen atoms of a methane molecule is replaced by chlorine, trichloromethane is formed.
→ CHCl 3 + HCl CH 2 Cl 2 + Cl 2 UV
63.
How is tetrachloromethane or carbon tetrachloride formed? When four hydrogen atoms of a methane molecule is replaced by chlorine, tetrachloromethane is formed.
→ CCl 4 + HCl CHCl 3 + Cl 2 UV
64.
What is homologous series? A homologous series is a family of organic compounds with the same general formula, similar chemical properties and successive members differing by – CH 2 .
65.
Name the homologous series of aliphatic hydrocarbons. Aliphatic hydrocarbons have three homologous series – Alkanes, Alkenes and Alkynes
66.
State the characteristics of members of a homologous series. a) They have properties that vary in a regular and predictable manner. b) They have similar chemical properties. c) They have gradually varying physical properties. d) Their formula fit the general molecular formula e) The adjacent members CH 4 and C 2 H 6 or C 5 H 12 and C 6 H 14 differ by one carbon and two hydrogen.
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Write the next homologue of Methane and Pentane Methane is CH 4 next homologue is CH 4 + CH 2 = C 2 H 6 (Ethane) Pentane is C 5 H 12 , next homologue is C 5 H 12 + CH 2 = C 6 H 14 (Hexane)
68.
Give the names and structural formulae of next two higher homologues of methane.
Ethane C 2 H 6 69.
and Propane C 3 H 8
What is unsaturated hydrocarbon? A hydrocarbon in which the two carbon atoms are connected by a double bond or a triple bond is called unsaturated hydrocarbon. Ex: Alkenes and Alkynes
70.
71.
Mention the differences between saturated and unsaturated hydrocarbons.
Saturated hydrocarbons
Unsaturated hydrocarbons
1. Hydrocarbons in which carbon atoms are linked by single covalent bonds.
1. Hydrocarbons in which carbon atoms are linked by double and triple covalent bonds.
2. Names of these hydrocarbons end with ‘ane’.
2. Names of these hydrocarbons end with ‘ene’ or ‘yne’
What are alkenes? Alkenes are unsaturated hydrocarbons in which the two carbon atoms are connected by double bond. The name of these hydrocarbons end with ‘ene’. Their general formula is C n H 2n . They are referred to as olefins. Ex: Ethene, Propene, Butene etc
72.
How is double bond formed in alkenes?
73.
In alkenes, two hydrogen atoms are less when compared to the saturated hydrocarbons. The two of the carbon atoms in the molecule is joined together by two covalent bonds. Thus a double bond is formed. Give reason: Ethene is said to be unsaturated. Ethene is said to be unsaturated because each molecule does have carbon-to-carbon double bond and has less maximum possible number of hydrogen atoms.
74.
The general formula of a homologous series of carbon compounds is Cn H2n . Write the molecular formula of the second and fourth member of the series. Second member is n=3, C 3 H 2x3 = C 3 H 6 Fourth member is n=5, C 5 H 2x5 = C 5 H 10
75.
What are alkynes?
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Alkynes are unsaturated hydrocarbons that contain one triple bond between carbon atoms. The name of these hydrocarbons end with ‘yne’. Their general formula is C n H 2n-2 . 76.
Ex: Ethyne, Propyne etc. Give the general name of the class of compounds having the general formula C n H 2n-2 . Write the first member of this homologous series. Alkynes. The first member is Ethyne.
77.
78.
Compare the characteristics of alkanes, alkenes and alkynes. Alkanes
Alkenes
Alkynes
They are saturated
They are unsaturated
They are unsaturated
They have single bond between carbon atoms
They have double bond between one of the carbon atoms
They have triple bond between one of the carbon atoms.
Their general formula is C n H 2n+2
Their general formula is C n H 2n
Their general formula is C n H 2n-2
Their names end with ‘ane’
Their names end with ‘ene’
Their names end with ‘yne’
Select the hydrocarbons which are members of the same homologous series. C 5 H 10 , C 3 H 8 , C 6 H 10 , C 4 H 10 , C 7 H 12 , C 8 H 16 Alkanes: C 3 H 8 and C 4 H 10 , Alkenes: C 5 H 10 and C 8 H 16 , Alkynes: C 6 H 10 and C 7 H 12
79.
Classify the following into saturated and unsaturated hydrocarbons – Benzene, cyclopropane, alkene and alkane, methane, ethene, Propyne, butene Saturated: Alkane, cyclopropane, methane Unsaturated: Benzene, alkene, ethene, Propyne, butene
80.
Classify the following compounds containing double bond and triple bond – Ethyne, benzene, Butyne, pentene Double bond: Benzene, pentene Triple bond: Ethyne, Butyne
81.
Give reason: Alkanes undergo only substitution reactions but alkenes and alkynes undergo both substitution and addition reactions. Alkenes and alkynes have double and triple bonds, which on breaking can add hydrogen atoms to satisfy the valency.
82.
What are Cycloalkanes? Cycloalkanes are closed chain saturated hydrocarbons having one ring and the general formula C n H 2n .
83.
Write the structural formula of the first member of Cycloalkanes.
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The first member of the Cycloalkanes is cyclopropane (C3H6). Its structure is
84.
Give reason: Alkenes and Cycloalkanes have same general formula. Alkenes and Cycloalkanes have same general formula because they have double bond between carbon atoms.
85.
Mention the differences between alkenes and Cycloalkanes.
Alkenes 1. They are unsaturated 2. They have double bond between carbon atoms 3. Their name end with ‘ene’. 4. They are acyclic. 86.
Cycloalkanes 1. They are saturated 2. They have single bond between carbon atoms. 3. Their names end with ‘ane’ 4. They are cyclic
Even though alkenes and Cycloalkanes have the same general formula, they are different. How? Alkenes are unsaturated where as Cycloalkanes are saturated.
87.
What are aromatic hydrocarbons or arenes? Aromatic hydrocarbons are hydrocarbons that have atleast one aromatic ring (benzene ring).
88.
Write the structure of the first member of the aromatic hydrocarbons. OR Explain the structure of benzene. Benzene is the first member of the aromatic hydrocarbon series. Its molecular formula is C 6 H 6 . A benzene molecule is made up of 6 carbon atoms and 6 hydrogen atoms. Its structural formula is as shown in the figure. A benzene ring has six carbon atoms with alternate single and double bonds.
89.
Cyclohexane does not belong to aromatic class even though it has a ring structure. How do you justify this? Cyclohexane is a saturated hydrocarbon in which the carbon atoms are joined by single covalent bonds to form a ring where as in aromatic hydrocarbons have alternate single and double bonds. Hence Cyclohexane is does not belong to aromatic class.
90.
Write the different type of representation of structure of benzene.
91.
or or Write the structure of Toluene.
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or 92.
Write the structure of Naphthalene.
93.
OR Mention the uses of Benzene a) Benzene is used as solvent for oils, fats, resins, rubber, sulphur, iodine etc. b) It is used in the manufacture of dyes, drugs, perfumes, explosives etc. c) It in used in preparation of gammexane, an insecticide.
94.
d) It is used for dry cleaning. Mention the uses of Toluene
95.
a) Toluene is used as a solvent for oils, fats, paints, lacquers, resins etc. b) It is used in the manufacture of TriNitroToluene (TNT) an explosive. Mention the used of Naphthalene a) Naphthalene is used as an insecticide in the form of moth balls. b) It is used in the synthesis of dyes.
(C) Functional Groups 96.
What are functional groups? Derivative hydrocarbons in which one or more hydrogen atoms have been replaced by atom or group of atoms of other elements are called functional groups. Functional groups are specific groups of atoms or bonds within molecules that are responsible for characteristics chemical reactions. Functional groups are the sites where reactions occur in organic molecules.
97.
On the basics of functional groups present, how are organic compounds classified? Alkyl / Aryl radical (Less reactive part) and Functional group ( Active part)
98.
What are alcohols? Write their general formula. Compounds containing –OH as the functional group are called alcohols. Their general formula is R – OH or C n H 2n+1 OH
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Even though NaOH & KOH contains –OH group. It is not included in the group of organic substances. Why? NaOH and KOH are strong bases which are ionic compound that contain OH ions. Alcohols are covalent compounds, even though they have on or more hydroxyl ( -OH ) functional group, they do not behave like bases. The – OH group attached to a carbon atom is a covalent bond.
100. Write the molecular formula of first five members of alcohol.
Name of Alcohol 1. Methanol 2. Ethanol 3. Propanol 4. Butanol 5. Pentanol
Molecular Formula CH 3 OH C 2 H 5 OH CH 3 CH 2 CH 2 OH or C 3 H 7 OH C 4 H 9 OH C 5 H 11 OH
101. Write the IUPAC name of the following compounds. a) C 2 H 5 OH – Ethanol
b) C 3 H 7 OH – Propanol
c) C 4 H 9 OH – Butanol
d) C 5 H 11 OH – Pentanol
102. What are aldehydes? Write their general formula. Compounds containing –CHO as the functional group are called aldehydes. Their general formula is R – CHO. 103. Write the molecular formula of first five members of aldehydes.
Name of Aldehyde 1. Methanal 2. Ethanal 3. Propanal 4. Butanal 5. Pentanal
Molecular Formula HCHO CH 3 CHO CH 3 CH 2 CHO CH 3 CH 2 CH 2 CHO CH 3 CH 2 CH 2 CH 2 CHO
104. What are carboxylic acids? Write their general formula. Compounds containing –COOH as the functional group are called Carboxylic acids. Their general formula is R – COOH. 105. Write the molecular formula of first five members of carboxylic acid. Name of carboxylic acid Molecular Formula
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1. Methanoic acid
HCOOH
2. Ethanoic acid
CH 3 COOH
3. Propanoic acid
C 2 H 5 COOH
4. Butananoic acidu
C 3 H 7 COOH
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C 4 H 9 COOH
106. Give the IUPAC name of the following compounds: a) HCOOH – Methanoic acid b) CH 3 COOH – Ethanoic acid
107. What are amines? Write their general formula. Compounds containing –NH 2 as the functional group are called amines. Their general formula is R –NH 2 108. Write the molecular formula of some members of amines. Name of amine
Molecular Formula
1. Methyl amine
CH 3 NH 2
2. Ethyl amine
C 2 H 5 NH 2
109. Name the members of the alkyl groups. Methyl, ethyl, propyl etc. 110. Name the members of aryl group. Compounds containing benzene ring are aryl group. 111. Name the functional groups present in the following compounds. a) CH 3 CHO – Aldehyde
b) CH 3 CH 2 COOH – Carboxylic acid
c) CH 3 CH 2 CH 2 OH – Alcohol
d) Methanal – Aldehyde
e) Methanol – Alcohol g) Amino acids – Amines
f) Methanoic acid – Carboxylic acid
112. Write the names of the following functional groups: a) − C ≡ C −
Alkyne
b) C = C
Alkene
c) – CHO
Aldehyde
d) – OH
Alcohol
e) – COOH
Carboxylic acid
113. Give one example each of the compounds having the following functional groups: a) Aldehyde group – Methanal b) Alcohol group – Methanol c) Carboxylic acid group - Methanoic acid 114. What are amino acids?
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Amino acids is a molecule that contains both amino (– NH 2 ) and carboxylic acid (– COOH) functional groups. 115. Name the simplest and the smallest amino acid found in protein. Glycine, Its formula is H 2 N – CH 2 – COOH 116. What are poly-functional compounds? Organic compounds having more than one functional groups are called polyfunctionsl compounds. Ex: Glycerol, Salicylic acid 117. Write the structure of glycerol or Write the structural formula of the compound having 3 – OH group.
118. Write the structural formula of the compound having one – COOH group.
119. Give reason: Ethanol cannot be called poly-functional compound. Ethanol has only one functional group – OH. 120. What is glycerol? Glycerol is a poly functional compound which is obtained as a byproduct of soap. It contains three hydroxyl groups. It is a trihydric alcohol. 121. What is salicylic acid? Salicylic acid is a poly functional compound which contains one – OH and one – COOH group. It is used in the production of aspirin.
122. Even though Methyl alcohol (CH3 OH) and Ethyl alcohol (C 2 H5 OH) contains –OH group. They are not called hydroxides but alcohols. Why? OR NaOH is not called as sodium alcohol. Why? OR CH 3 OH is not called Methyl hydroxide but Methyl alcohol. Why?
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In Methyl alcohol and Ethyl alcohol, hydroxyl group is just a group of atoms –OH which is covalently bonded to a carbon atom. In hydroxides –OH is a hydroxyl ion which is formed by ionic bond. Hence methyl alcohol and ethyl alcohol are not called as hydroxides.
(D) Hydrogenation of Oils 123. What are fatty acids? Long chain alkanes or alkenes if contain a terminal carboxylic acid group( – COOH ) are called fatty acids. 124. What are glycerides? How are they formed? Glycerides are fats or oils. When fatty acids react with trihydric alcohol like glycerol to form ester called glycerides. 125. How are fats and oils formed? When fatty acids react with glycerol, fats and oils are formed. Esterification Fatty acid + Glycerol → Fat/oil + Water
126. Write the molecular formula and structure of Stearic acid. Stearic acid is a saturated fatty acid. Its molecular formula is C 17 H 35 COOH. Its structure is
127. Why is Stearic acid a saturated fatty acid? Stearic acid does not contain double bonds in its carbon atom hence it is a saturated fatty acid. 128. Mention the differences between fats and oils. Fats
Oils
Fats are mostly saturated
Oils are mostly unsaturated
They are solids at room temperature They are liquids at room temperature They are chemically inactive
They are chemically reactive
They are digested slowly
They are digested fast
They have longer shelf life
They have short shelf life
It is easy to transport
It is difficult to transport
129. Give reason: a) Oils are easy to digest. Unsaturated oils are easy to digest because they are chemically reactive. b) Fats are digested slowly. Fats are saturated, they are chemically inactive hence they are digested slowly. c) Oils have short shelf life. Unsaturated oils have short shelf life because they undergo oxidation in air and produce a foul smell. d) Fats are easy to transport.
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Fats are solids at room temperature and have more shelf life as they are chemically inactive. Hence it is easy to transport, 130. What is meant by rancidity of oils? Rancidity is the process which causes a substance to become rancid, that is, having unpleasant smell or taste. 131. What is meant by hydrogenation of oils? The process of converting liquid oils into solids saturated fats by passing hydrogen gas through them is called hydrogenation of oils. Finely divided nickel is used as catalyst during the process. Ex: Vanaspathi
132. What is meant by hydrogenation reaction? The reactions in which hydrogen atoms are added are called hydrogenation reactions. Ex: Addition of hydrogen to make Alkyne into Alkene, Addition to hydrogen to make benzene into Cyclohexane. 133. Why is hydrogenation done? OR What is the importance of hydrogenation? a) Hydrogenated oil has longer shelf life and will not go rancid quickly. b) It also has a higher melting point and hence used in frying and pastries. 134. Give reason: Hydrogenated Oils are often used in frying and pastries. Hydrogenated oils have a higher melting point. Hence it is used for frying and pastries. 135. What is meant by saponification? The process of neutralizing the fatty acids present in oils or fats by adding sodium or potassium hydroxide is called saponification. 136. Explain the steps involved in saponification. Saponification is the reaction that takes place between oil and sodium hydroxide during the manufacture of soap. The steps involved are: 1) Hydrolysis of fats or oil into carboxylic acid and glycerol. 2) Neutralization of the fatty acid by sodium hydroxide. 137. What is meant by saponification value? Saponification value can be defined as the amount of potassium hydroxide in ‘mg’ (milligrams) required to neutralize the fatty acid present in one gram of oil or fat. 138. Why is the knowledge of saponification value of oil important?
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Saponification value helps the manufacturer of soap to prepare soap which does not contain excess of potassium hydroxide. 139. Mention the importance of fats and oils? a) Fats and oils are sources of food in which vitamin A, D, E & K are soluble. b) It is also a source of light for tribal people. c) Eskimos use animal fat as a source of light in their igloos. d) It is also used as a source of heat. 140. How are paraffin wax and beeswax different? Paraffin wax is a hydrocarbon. Beeswax, a natural wax is mainly made of esters of fatty acids and various long chain alcohols. 141. Mention the uses of beeswax. Beeswax is used in cosmetics, preparation of drip less candles and skin ointments.
142. Give reason: Hydrocarbon oils are not oils. As they do not contain fatty acids. 143. What is PUFA? PUFA stands for Poly Unsaturated Fatty Acid. It is an unsaturated hydrocarbon chain. Because of the presence of double bonds, it is reactive. This makes them more reactive than saturated fatty acids. They are susceptible to attack by free radicals which cause aging, hormone imbalance and immune disorders. Molecular & Structural formula: Sl.No
Compound
Molecular formula
1.
Methane
CH 4
2.
Ethane
C2H6
3.
Propane
C3H8
4.
Butane
C 4 H 10
5.
Pentane
C 5 H 12
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6.
Ethene
C2H4
7.
Propene
C3H6
8.
Butene
C4H8
9.
Pentene
C 5 H 10
10.
Ethyne
C2H2
11.
Propyne
C3H4
12.
Butyne
C4H6
13.
Pentyne
C5H8
14.
Cyclopropane
C3H6
15.
Cyclobutane
C4H8
16.
Cyclopentane
C 5 H 10
17.
Cyclohexane
C 6 H 12
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18.
Benzene
C6H6
19.
Toluene
C 6 H 5 CH 3
20.
Naphthalene
C 10 H 8
21
Glycerol
C3H8 O3
22
Salicylic acid
C7H 6O3
132
Fill in the blanks: 1. 2.
The most common alloy of carbon and iron is steel. The valency of carbon is four.
3. 4.
The second strongest bond between like atoms is C-C bond. The crystalline forms of carbon are diamond and graphite.
5.
The nature of chemical bond present in organic compounds is covalent bond.
6.
The bond angle between H-C-H in methane molecule is 109o28|.
7.
The electronic configuration of carbon is 1s , 2s 2p
8.
The electronic configuration of carbon in excited state is 1s , 2s 2px 2py 2pz
9.
The ability of carbon atoms to link together to from short or long chain by covalent bond is called catenation.
10.
The property of carbon atoms to form long chains in compounds is called catenation.
11.
Organic compounds having same molecular formula with different structural arrangement of atoms in them is known as isomerism.
12.
The number of organic compounds increases due to the phenomenon of isomerism.
2
2
2 2
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1
1
1
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13.
The person who suggested that organic compounds are derived from organisms is Berzelius.
14.
The first organic compound which was synthesized from inorganic compound was urea.
15. 16.
The person who synthesized urea from ammonium cyanate was Friedrich Wohler. Friedrich Wohler prepared the organic compound urea.
17. 18.
The unique properties of carbon atom are catenation, tetravalency and isomerism. The study of compounds and reactions involving carbon is called Organic chemistry.
19.
An example of an organic compound present in our food is starch.
20. 21.
Simplest binary organic compounds containing carbon and hydrogen only are called hydrocarbons. Compounds of carbon with hydrogen alone are called hydrocarbons.
22. 23.
IUPAC stands for International Union of Pure and Applied Chemistry. An example of a hydrocarbon in gaseous form is methane/ propane.
24.
An example of a hydrocarbon in liquid form is hexane/benzene.
25. 26.
An example of a hydrocarbon in solid form is wax/naphthalene/asphalt. An example of a hydrocarbon which is a polymer is polyethylene.
27.
Hydrocarbons have a characteristic odour only in vapour state.
28. 29. 30.
The main source of the world’s electric energy and heat source is hydrocarbons. The two principal sources of hydrocarbons are petroleum and coal. Aliphatic hydrocarbons are mainly obtained from petroleum.
31. 32.
Aromatic hydrocarbons are mainly obtained from coal. Saturated hydrocarbons are referred to as paraffins.
33.
The general formula of alkanes is C n H 2n+2
34.
Hydrocarbons having the general formula C n H 2n+2 are called alkanes.
35.
Alkenes are referred to as olefins.
36. 37. 38.
The first member of the alkanes or saturated hydrocarbon is methane. Carbon compounds have usually low melting points and boiling points. Two adjacent homologues differ by 1 carbon atom and 2 hydrogen atoms.
39.
The unsaturated hydrocarbons having double bond between carbon atom are alkene.
40. 41.
The general formula of alkene is C n H 2n . The hydrocarbon having the general formula C n H 2n is alkene.
42.
The first member of the alkene hydrocarbon group is Ethene.
43.
The unsaturated hydrocarbons having one triple bond between carbon atoms are alkynes.
44.
The general formula of alkynes is C n H 2n-2
45.
The first member of the alkyne series is Ethyne.
46.
In homologous series one member differs from the preceding member by a CH 2 group.
47.
The derivatives of a series of hydrocarbons whose simplest member is benzene is Aromatic hydrocarbons.
48.
Benzene ring was proposed by Kekule.
49.
The active part of an organic compound is the functional group.
50. 51.
The less reactive part of an organic compound is the alkyl/aryl part. Compounds containing – OH group as functional group are called alcohols.
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52.
The functional group present in CH 3 OH is alcohol.
53.
Compounds containing – COOH group as functional group are called Carboxylic acids.
54.
Compounds containing – CHO group as functional group are called Aldehydes.
55.
Compounds containing – NH 2 group as functional group are called amines.
56.
The compound containing three carbon alcohol is Propanol.
57. 58.
Organic compounds having more than one functional groups are called poly-functional compounds. An example of a poly-functional compound is amino acid.
59.
A compound having 3 – OH functional group is Glycerol.
60.
The by-product of preparation of soap is Glycerol.
61.
A poly-functional compound containing one – OH group and one – COOH group is Salicylic acid.
62.
Long chain alkanes or alkenes containing terminal carboxylic acid ( – COOH) are called fatty acid.
63.
Fatty acids react with trihydric alcohols to form glycerides.
64.
The formula of Stearic acid is C 17 H35 COOH
65. 66. 67.
Oils are unsaturated and liquids at room temperature. Fats are saturated and solids at room temperature. The process in which oils undergo oxidation and produce a foul smell is called rancidity.
68.
The process of converting liquid oil into solids saturated fats by passing hydrogen gas is called hydrogenation.
69.
A reaction in which hydrogen atoms are added is called hydrogenation reaction.
70.
The process of neutralizing the fatty acids present in the oils or fats by adding sodium hydroxide is called saponification.
71.
PUFA stands for Poly unsaturated Fatty Acid.
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Chapter 13: Industrial organic Chemistry
C13
1. What is sucrose? Sucrose is a disaccharide. It is made up of two mono saccharides glucose and fructose. 2.
Write the balanced chemical equation for the reaction when glucose combines with fructose to give sucrose. C 6 H 12 O 6 + C 6 H 12 O 6 → C 12 H 22 0 11 + H 2 O
3.
Name the two main sources of sucrose. The two main sources of sucrose are cane sugar and beet root sugar.
4.
How are carbohydrates classified? Carbohydrates are classified based on the number of sugar units into monosaccharides, disaccharides and polysaccharides.
5.
Why is the use of jaggery recommended than white crystalline sugar? Jaggery is recommended than white crystalline sugar because of the presence of useful nutrients in addition to carbohydrates.
6.
What is caramel? The sticky substance formed when sugar is heated to about 473K is called caramel.
7.
Why is caramel used in making chocolates and candies? Caramel imparts a characteristic colour and flavour to chocolates and candies.
8.
How does high concentration of sugar act as a preservative of food? High concentration of sugar prevents the growth of micro-organisms. Hence it can be used as a preservative.
9.
Give reason: a) Fruit juices mixed with sugar should be consumed quickly. If fruit juices mixed with sugar are stored for hours or days, they turn sour and give a different taste. b) Thick sugar syrup can store fruit juices for many days. Sugar tends to draw water from the microbes. This process leaves the microbial cells dehydrated, thus killing them. In this way, the food will remain safe from microbial spoilage c) The shelf life of sucrose is more than that of jaggery. Jaggery absorbs the moisture and starts to ferment in rainy season. In sucrose the water content is removed. Hence it can be stored for a longer time.
10.
What is the need for the use/manufacture of sugar?
11.
When compared to jaggery, sugar has a greater shelf life and it can be stored easily in any climatic condition. What is meant by fermentation i? The aqueous solution of sugar undergoes chemical reaction called fermentation.
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In which form do carbohydrates get assimilated in our body? Carbohydrates in the form of starch, disaccharides and mono saccharides get assimilated by our body.
13.
What is starch?
14.
Starch is a natural polymer formed by many units of mono saccharides. What happens when a few drops of concentrated sulphuric acid is added to a test tube containing starch? Hydrogen and oxygen present in carbohydrates are absorbed by sulphuric acid in the form of water. Black carbon residue is left behind.
15.
What happens when quick lime is added to a test tube containing glucose and gently heated? Quick lime is a drying agent. It does not get charred.
16.
Give reason: Sulphuric acid added to a test tube containing glucose gets charred but not when quick lime is added. Sulphuric acid is a dehydrating agent so it absorbs hydrogen and oxygen present in glucose. But quick lime is only a drying agent so it does not get charred.
17.
What is the difference between drying agent and dehydrating agent? Drying agent Drying agent simply removes excess water present in a substance which is not chemically bound to it.
Dehydrating agent Dehydrating agents remove water which is chemically bound to a substance. Ex: Sulphuric acid
Ex: Quick lime 18.
Mention the steps involved in the manufacture of sucrose or common sugar. a) Extraction of juice from sugarcane or beet root. b) Purification of juice. c) Concentration and crystallization.
19.
d) Separation and drying of crystals. Briefly explain the manufacture of sucrose or common sugar. a) Sugarcane or sugar beet is cut into pieces, crushed in a series of roller mills. b) The juice is warmed and run into settling tanks. c) It is decanted from the sediment and made alkaline with calcium hydroxide. d) The impurities get precipitated. e) The liquid is steamed to coagulate protein matter and allowed to settle. f) The clear juice is concentrated into syrup by evaporation under reduced pressure. The syrup is cooled to crystallize into sugar. g) The crystals are dissolved in hot water and decolourised with animal charcoal or with coconut shell charcoal. It is then filtered. h) Hydrosol or sodium bi sulphate is added which generates sulphur dioxide which removes colour impurities. i)
The filtrate is concentrated and evaporated under reduced pressure to get syrup.
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j) The syrup is crystallized to get white crystals of sugar. What is bagasse? Bagasse is the cellulose material of the sugarcane residue.
21.
What is celotex? Celotex is a type of cardboard prepared by using bagasse as raw material.
22.
What is norit? The coconut shell charcoal used to decolourise sugar is called norit.
23.
What is hydrosol? What is its use? Hydrosol is chemically sodium bi sulphate. It is added to lighten the colour of jaggery or sugar during its manufacture.
24.
What is molasses? The uncrystallised syrup left behind in the form of brown viscous liquid is molasses.
25.
What is the role of animal charcoal or coconut shell charcoal in the manufacture of sugar? Animal charcoal or coconut shell charcoal is used as a decolouring agent in the manufacture of sugar. It makes sugar white.
26.
Give reason: Evaporation of sugarcane juice is done under reduced pressure. When sugarcane juice is evaporated under reduced pressure, boiling takes place at a lower temperature and sugar can be obtained at a lower temperature.
27.
Mention a test for sugar/sucrose. OR How do you test the presence of sugar in a banana? OR How do to test a blood/urine sample of a diabetic person for sugar? Take an aqueous solution of the sample to be tested and mix it with hydrochloric acid. Add Fehling’s solution (Alkaline copper sulphate solution). If reddish precipitate is obtained, it indicates the presence of sugar/sucrose in the given sample.
28.
Define fermentation. Fermentation is a chemical decomposition produced by micro-organisms on certain organic matter.
29.
On what factors does fermentation depend? Fermentation depends on: a) Suitable temperature range. b) Dilution of matter.
30.
Mention the steps involved in the fermentation of molasses. a) Dilution of molasses by water such that the solution contains about 10% sugar. b) Addition of yeast and maintaining the temperature range of 308K to 313K. c) Distillation of the fermented matter.
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Briefly explain how Ethyl alcohol or ethanol is prepared. a) Molasses is diluted with water and acidified by adding dilute sulphuric acid. b) Yeast is added to the solution and the container is closed. c) The temperature is maintained around 308K. d) Fermentation takes place in about a week. It contains 6% – 10% alcohol. e) It is fractionally distilled to obtain 95% alcohol. Enzyme C12H22 O11 + H2 O → C6H12 O6 + C6H12 O6 Invertase
Sucrose
Glu cos e
+ Fructose
Enzyme → C2H5 OH + 2CO2 ↑ C6H12 O6 Zymase
→ Ethanol + Carbon dioxide Glu cos e / Fructose 32.
What is wort? During the manufacture of ethyl alcohol or ethanol, the fermented matter is called wort.
33.
State the function of the following: a) Steaming in the process of manufacture of sucrose: It is used to coagulate proteins and make them settle. b) Enzyme invertase in the manufacture of ethanol: It converts sucrose into glucose and fructose.
34.
c) Enzyme zymase in the manufacture of ethanol: It converts glucose/fructose into ethanol. Give reasons: Milk turns into curds very quickly and becomes sour in summer. Milk turns into curds when the temperature is around 30-40 °C which promotes the growth of bacteria (Lactobacillus). Hence milk turns into curds very quickly in summer.
35.
A small quantity of curds is added to milk. The mixture is kept in the refrigerator for about 4 hours. When it is taken out, it is observed that it has not curdled completely. Give scientific reason. When the mixture of milk and curds is kept in the refrigerator, the temperature is about 6 o o to 8 c. For the conversion of milk to curds a temperature of 30-40 c is necessary. Hence it is curdled completely.
36.
How is ethanol being used as a fuel? Ethanol / Ethyl alcohol is being blended with diesel and used as fuel by KSRTC of Karnataka.
37.
How is ethanol or ethyl alcohol used in ayurveda? In many ayurvedic tonics, alcohol is present in small extent. It stimulates and improves appetite.
38.
Give reason: The use of ethanol as fuel conserves fossil fuels. Ethanol is a good fuel. It can be mixed with diesel and used as fuel. Hence it reduced the dependency on fossil fuels.
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Fill in the blanks: 1. 2.
Sucrose is a disaccharide. The two main sources of sucrose are cane sugar and beet root sugar.
3.
The vegetable that contains more sucrose is beetroot.
4.
The molecular formula of sucrose is C12 H 22 O 11 .
5. 6.
Sucrose consists of two mono saccharides. The sticky substance formed when sugar is heated to about 473K is called caramel.
7.
The protein matter in the sugarcane juice is coagulated by steaming.
8. 9.
The substance used to make hard boiled sugar candy is caramel. The duration for which a food item can be preserved is called shelf life.
10.
Hydrogen and oxygen in carbohydrates are present in the ratio 2:1.
11.
Humans cannot digest carbohydrates in the form of cellulose.
12. 13. 14. 15.
Carbohydrates get assimilated in our body in the form of glucose. Humans can digest carbohydrates in the form of starch, disaccharides and mono saccharides. The fibrous matter present in vegetables is cellulose. An example of a natural polymer formed by many units of monosaccharides is starch.
16. 17.
Sucrose is made of one unit of glucose and one unit of fructose. An example of a good dehydrating agent is concentrated sulphuric acid.
18.
An example of a drying agent is Quick lime.
19.
The cellulose material of the sugar cane residue is called bagasse.
20.
The residue of sugarcane from which the juice is extracted can be used to prepare cardboard.
21.
Bagasse is used as a raw material to prepare cardboard.
22. 23. 24.
Bagasse is used as a raw material to prepare cardboard known as celotex. A type of cardboard prepared by using bagasse as raw material is celotex. The coconut shell charcoal used to decolourise sugar is called norit.
25.
Hydrosol is chemically sodium bi sulphate.
26.
The substance added to lighten the colour of jaggery or sugar during its manufacture is hydrosol or sodium bi sulphate.
27.
The uncrystallised syrup left behind in the form of brown viscous liquid is called molasses.
28.
The molecular formula of ethanol/ethyl alcohol is C 2 H 5 OH
29.
Molasses is used to prepare ethyl alcohol.
30. 31.
The raw material used to manufacture ethyl alcohol is molasses. The chemical added to test the presence of sugar are hydrochloric acid and Fehling’s solution.
32.
The colour observed when hydrochloric acid and Fehling’s solution is added to test sugar is reddish.
33.
The word fermentation is derived from Greek language which means boiling.
34.
The chemical decomposition produced by micro-organisms on certain organic matter is called fermentation.
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35. 36.
The by-product of fermentation is carbon dioxide. The matter which undergoes fermentation is called substrate.
37.
The temperature range necessary for fermentation of molasses is 308 K to 313K.
38. 39.
During the manufacture of molasses, it is acidified using dilute sulphuric acid. The fermented matter during the manufacture of molasses is called wort.
40.
The enzyme which converts sucrose to glucose and fructose is invertase.
41. 42.
Invertase converts sucrose to glucose. The enzyme which converts glucose to ethanol is zymase.
43. 44.
Zymase converts glucose/fructose into ethanol. The substance which is used in Ayurveda to stimulate and improve appetite is alcohol. *****
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Chapter 14: Sound 1.
P14
How does study of sound help us? a) Study of sound produced by heart and lungs can signal the medical problems. b) Study of properties of sound helps in improvement of acoustics in theatres, concert halls.
2.
What is an echo? The sound heard after reflection from a rigid surface is called an echo.
3.
Write the formula to find the time taken by an echo.
time =
4.
Total dis tance travelled 2d = Speed of sound v
Derive the minimum distance required for an echo to be heard. The sensation of sound persists in our ear for about 0.1s. To hear a distinct echo, the time interval between the original sound and the reflected sound must be later or equal to 0.1s. -1 By substituting t=0.1s and v=340ms in air
= d
5.
340x0.1 = 17m 2
What are the conditions necessary for an echo to be heard? a) The time interval between the original sound and the reflected sound must be later or equal to 0.1s. b) The minimum distance between the reflecting surface and the source must be 17m.
6.
Why is an echo weaker then the original sound? Sound waves carry energy. When sound waves hit a reflecting surface, it imparts energy to the surface from which it bounces.
7.
A boy standing in front of a hill claps. He hears an echo after two seconds. The -1 speed of sound in air is 340ms . What is the distance of the hill from him?
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Give reason: Sometimes echoes are heard more than once. Echoes heard more than once is due to multiple reflections from number of reflecting surfaces.
9.
Why do we hear roaring of thunder? Roaring of thunder is due to multiple reflections of sound from many reflecting surfaces of clouds.
10.
Give two examples where multiple echoes are heard. a) In the whispering gallery of Golgumbuz at Bijapur, sound is echoed seven times. b) Echo produced by mountain Lake Killarney in Ireland is repeated almost hundred times.
11.
How is sound produced? Sound is produced when a body vibrates in a particular range of frequency.
12.
What is meant by audible range? The range of frequency from 20Hz to 20,000 Hz (20 kHz) is called audible range. Or human audible frequency.
13.
What is infrasonic or subsonic sound? Sounds of frequency below 20Hz are called infrasonic sound or subsonic sound.
14.
What are ultrasonic sounds? Sounds of frequency beyond 20,000Hz (20 kHz) are called Ultrasonic sounds.
15.
What is ultrasonics? The branch of science that deals with ultrasound is called ultrasonics.
16.
Name some animals that can hear ultrasonic sounds. Animals like dogs, cats and bats.
17.
What is the difference between normal sound and ultrasonic sounds? Normal sounds have low frequency where as ultrasonic sounds have high frequcncy.
18.
Give reason: Ultrasonic sounds have high frequency. Ultrasonic sounds have high frequency because it has high energy.
19.
How can ultrasonic sounds be produced? A thin quartz slice is placed between two thin metallic plates. The metallic plates are connected to an A.C. source frequency more than 20 kHz. When the current flows through the metallic plates, the quartz slice vibrates with a frequency more than 20 kHz and produce ultrasonic sound.
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Mention the uses of ultrasonic waves. a) By studying the ultrasonic waves passing through a medium, we can infer about its physical properties like elasticity, configuration of atoms. b) They can be used to detect cracks and flaws in metal mouldings. c) They are used in homogenizing two immiscible liquids. d) They are used in manufacturing of alloys. e) They are used in manufacturing emulsion for photographic films. f) They are used in dry cleaning to remove grease and dirt. g) They serve as insect repellants. h) They are used for sterilization purposes. i) They are used to cure neuralgic and rheumatic pains. j)
They are used in bloodless surgery.
k) They are used to break gallstones. 21.
How are bats able to navigate with ultrasonic waves? Bats produce and hear sounds of frequency upto 100 kHz. The sound produced by flying bats gets reflected from obstacle in front of it. By hearing this reflected sound it can detect obstacle even during night.
22.
Mention the industrial uses of ultrasonic waves. a) They can be used to detect cracks and flaws in metal mouldings. b) They are used in homogenizing two immiscible liquids. c) They are used in manufacturing of alloys.
23.
Mention the medical uses of ultrasonic waves. a) They are used for sterilization purposes. b) They are used to cure neuralgic and rheumatic pains. c) They are used in bloodless surgery. d) They are used to break gallstones.
24.
Give reason: Ultrasonic waves are used in sterilization. Ultrasonic waves can kill bacteria. Hence it is used for sterilization purpose.
25.
What is the minimum frequency of sound wave needed to prepare emulsion from two immiscible liquids? Greater than 20 kHz.
26.
Expand SONAR. SONAR stands for SOund Navigation And Ranging.
27.
What is SONAR? SONAR is a technique by which ultrasonic waves are used to measure the distance, direction and speed of underwater objects.
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28.
What are the uses of SONAR?
29.
Sonar is used to locate underwater hills, valleys, submarines, icebergs and sunken ships. Explain how the depth of underwater objects is measured using sonar. Sonar consists of a transmitter and a detector installed on a boat/ship. The transmitter produces and transmits ultrasonic waves. These waves travel through water until they strike an object or floor of the sea or ocean. They get reflected and the reflected waves return to the sonar. They are sensed by the detector. The detector converts the ultrasonic waves into electrical signals which are interpreted. The time interval between transmission and reflection is recorded and the depth or distance is calculated.
30.
Write the formula to calculate the depth of sea/ocean or underwater objects. Distance of the objects is given by d =
31.
vxt 2
What is meant by echo-ranging? Echo ranging is a technique of using ultrasonic waves used to calculate the distance of objects.
32.
A ship sends ultrasonic sound, it returns from seabed and its is detected after 4s. If -1 the speed of ultrasonic sound through seawater is 1.5kms . What is the depth of the sea?
33.
The ultrasonic signal send by sonar takes 3 seconds to return. Find the distance of the object if the velocity of sound in water is 1.5km/s.
34.
Ultrasonic waves emitted at the ocean water take 3.5 seconds to return. Find the depth of ocean.
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35.
A ship on the surface of a sea sends an ultrasonic signal vertically downwards into the sea. The signal is reflected from a submarine and is received after 2 seconds. Calculate the depth (in km) of the submarine. [Assume the velocity of sound in water=1450m/s]
36.
An ultrasonic sound sent from a ship travels with the speed of 1530 m/s in sea water. How deep is the water if the time delay of the echo from the sea bed is 6 seconds?
37.
What is ultrasound scanning? The technique used to get images of internal organs of human body is called ultrasound scanning.
38.
Give reason: Ultrasound scanning is widely used than x- rays. Ultrasound scanning is less harmful than x-rays. Hence it is widely used.
39.
What is echo Cardiograph? Echo cardiograph is a technique which uses ultrasound to examine the heart.
40.
Mention the application of ultrasound scanner. a) Ultrasound scanner is used to get the images of internal organs of human body like bladders, kidneys, ovaries. b) It is used to examine the heart. c) It is used in examination of the foetus during pregnancy to detect congenial and growth abnormalities.
41.
How does ultrasound scanner work? Ultrasound scanner probe is placed over the part of the body to be examined. Lubricating jelly is put on the skin so that the probe makes good contact with the body. The probe is
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connected by wire to the ultrasound machine and monitor. Pulses of ultrasound are sent from the probe to the body. Ultrasound waves bounce back from the various structures in the body. This is detected by the probe and the image is displayed on the monitor. What is the principle of ultrasound scanner? Ultrasound waves travel through fluid and soft tissues, but are reflected back when it hits dense surface.
43.
What is Doppler Effect? Doppler effect is the apparent change in the frequency of wave motion due to relative motion between the source of sound and the observer.
44.
When can we observe Doppler Effect? Doppler Effect is observed when either the source or the observer or both are in relative motion.
45.
Explain Doppler Effect with an example. Example 1: When a speeding fire engine/ambulance passes a stationary observer, the pitch of the siren drops as it passes the observer. The waves in front appear to be compressed and the observer feels the pitch to be higher. When the fire engine/ambulance passes the observer, the waves behind the engine appear to be far apart. So the observer feels the pitch lower. Example 2: A person standing on the railway platform feels a change in the pitch of the whistle of a train which is moving past the observer. The pitch of the whistle appears to be lower as the engine passes the person.
46.
Give reason: a) A person in the front of an engine feels the pitch of whistle of the train higher. When the engine is moving, the waves in front appears to be compressed. b) A person behind the engine feels the pitch of the whistle of an engine to the lower. When the engine moves past a person, the waves behind the engine appears to be faster apart.
47.
Mention the applications of Doppler Effect. a) Doppler Effect can be used to track artificial satellites. b) It can be used to determine the velocity of submarines. c) It can be used to calculate the speed at which the objects of the universe are receding from us. d) It can be used to gauge the movements of stars with relative to the earth.
48.
Mention the uses of Doppler Effect in astrophysics. a) It can be used to calculate the speed at which the objects of the universe are receding from us. b) It can be used to gauge the movements of stars with relative to the earth.
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49.
What is meant by red shift?
50.
When a source of light moves away from the observer with a velocity comparable to that of light, the frequency of the light noticed will be less. It shifts towards the red end of the spectrum. This effect is called red shift. What is the significance of red shift? The study of the spectrum of the stars indicated that all stars in the universe are moving away from us at very high speed. This indicated that the universe is expanding.
51.
What is meant by blue shift? When the source of light wave approaches the observer with a velocity comparable to that of light, the frequency of light noticed is high. It shifts to blue end of the spectrum. This shift is called blue shift.
52.
Give reason: Ultrasonic waves cannot be used to track artificial satellites. Ultrasonic waves require a material medium for its propagation. Ultrasonic waves also lose energy to the medium in which they travel. Hence ultrasonic waves cannot be used to track satellites.
53.
Expand RADAR. RADAR stands for RAdio Detection And Ranging.
54.
What is RADAR? Radar is a device which uses electromagnetic waves (radio waves) in place of ultrasonic waves to determine the range, altitude, direction or speed of moving objects.
55.
Give reason: Radio waves are used to track artificial satellites. Radio waves are electromagnetic waves which can travel through vacuum and also very large distances. Hence Radiowaves are used to track artificial satellites.
56.
Give reason: We require an accurate instrument which can measure radar. The time taken by radar to cover distance is very less as it travels with the speed of light. Hence very accurate instrument which can measure very small time interval of the order of microseconds is necessary.
57.
Explain how radar works. Radar makes use of pulse of waves from an antenna and detects the reflected wave after it bounces odd the target. By knowing the speed of radio waves and the tome taken for the signal to bounce off the object and hit the receiver, the distance of the object can be detected.
58.
Mention the uses of Radar. Radar is used to track aircraft, artificial satellites and motor vehicles.
59.
What is radar gun? Radar gun is an instrument used to determine the speed of moving objects like vehicles.
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How do traffic authorities use radar/ Doppler Effect to detect speed of vehicles? Radiowaves are sent in the direction of speeding vehicles and the reflected waves are received. The change in the frequency of the waves is used to determine the speed of vehicles.
Fill in the blanks: 1.
The sound heard after reflection from a rigid surface is called an echo.
2.
The formula to find the time taken by an echo is t =
3.
The sensation of sound persists in our ear for about 0.1seconds.
4.
The time interval between the original sound and the reflected sound for an echo to be heard is >=0.1s.
5.
The minimum distance between the reflecting surface and the source for an echo to be heard must be 17m.
6.
More than one echo is heard due to multiple reflections from the reflecting surfaces.
7.
In the whispering gallery of Golgumbuz at Bijapur, sound is echoed seven times.
8. 9. 10.
The human audible frequency range is 20Hz to 20,000 Hz. Sounds of frequency below 20Hz are called infrasonic sound or subsonic sound. Sounds of frequency beyond 20,000Hz (20 kHz) are called Ultrasonic sounds.
11.
The branch of science that deals with ultrasound is called ultrasonics.
12.
Animals that can hear ultrasonic sound is dogs/ cats/ bats.
13. 14. 15.
Ultrasonic waves have high frequency because it has high energy. Bats can produce and hear sounds of frequency upto 100 kHz. The wave used to detect cracks and flaws in metal mouldings is ultrasonic waves.
16.
Two immiscible liquids can be homogenized by using ultrasonic waves.
17. 18.
The wave used in manufacture of emulsion for photographic films is ultrasonic waves. The wave used in manufacture of emulsion for photographic films must have frequency greater than 20kHz.
19. 20. 21.
The wave used in insect repellant is ultrasonic waves. The wave used in sterilization is ultrasonic waves. The wave used in bloodless surgery is ultrasonic waves.
22.
The wave used to break gallstones is ultrasonic waves.
23.
A device which uses ultrasonic sound waves to measure the distance of an object is SONAR.
24. 25. 26.
SONAR stands for Sound navigation and ranging. The formula used to find depth of A wave having a frequency of 30 kHz belongs to ultrasonic sound.
27.
Sound propagates with maximum velocity (speed) through solids.
28. 29. 30.
Echo cardiograph by ultrasound waves is helpful in the study of heart. The technique used to study heart diseases is echo cardiography. The working principle of radar gun is Doppler Effect.
31.
Doppler Effect in sound is observed as a change in its pitch.
32.
The wave used in radar gun used by traffic police to detect over speeding vehicles is Radiowaves.
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33. 34.
The name of sound waves whose frequency is grater than 20 kHz is ultrasonic sound. Doppler Effect of light can be applied in the study of stars.
35.
A strong beam of ultrasonic waves kill bacteria – this property is used in sterilization.
36. 37.
Gallstones in a person can be removed by using ultrasonic waves. The unit related to waves used by traffic police to detect the speed of vehicle is Hertz.
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Chapter 15: Metals 1.
Mention the differences between physical properties of metals and non-metals. Metals
2.
Non-metals
1. Metals are solids at solids at room temperature (except mercury & gallium)
1. Occurs as solids, liquids & gases
2. Sonorous
2. Non sonorous
3. Generally malleable & ductile
3. Non-malleable & non-ductile, brittle
4. Generally good conductors of electricity
4. Non conductors of electricity (except graphite)
5. Generally good conductors of heat
5. Non conductors of heat (except graphite & diamond)
6. Lustrous
6. Non lustrous
Mention the differences between chemical properties of metals and non-metals. Metals
3.
C15
Non-metals
1. They donate electrons
1. They accept electrons
2. They are electropositive
2. They are electronegative
3. They form ionic bond
3. They form both ionic and covalent bond
4. Generally they displace hydrogen from dilute acids (except copper, gold, silver, platinum)
4. Do not displace hydrogen from dilute acids.
5. Aqueous solution of metal oxides turns red litmus blue.
5. Aqueous solution of non-metal oxides turns blue litmus red.
6. Some metal oxides of metals in aqueous solution react with zinc to produce hydrogen.
6. Aqueous solution of oxides of nonmetals reacts with carbonates producing carbon dioxide.
Which property of metals is used in the following? a) Silver foil is spread over sweets – Metals are malleable b) Copper is used as cables – Metals are good conductors of electricity c) Aluminium is used in making utensils – Metals are good conductors of heat d) Gold is used in making ornaments – Metals are lustrous
4.
Give reason: a) Metals are electropositive. Electropositive element has the tendency to lose electrons and form cation.Metals are electron donors. Hence they are electropositive. b) Non-metals are electronegative. Electronegative element has the tendency to gain electrons and form anions. Non-metals are electron acceptors. Hence they are electronegative. c) Even though hydrogen is a non-metal, it is electropositive. At low temperatures hydrogen shows metallic properties.
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d) Sodium is electropositive. Sodium is electropositive because donates electrons from last orbit to another element and becomes electropositive. 5.
What are amphoteric oxides? Oxides of zinc and aluminium are called amphoteric oxides.
6.
Classify the following into acidic, basic, neutral and amphoteric oxides. Magnesium oxide, carbon dioxide, carbon monoxide, sulphur dioxide, zinc oxide, calcium oxide. Acidic oxide –Sulphur dioxide, carbon dioxide Basic oxide – Magnesium oxide, Calcium oxide Neutral oxide – Carbon monoxide. Amphoteric oxide – Zinc oxide.
7.
Which property of copper and aluminium makes them suitable? a) For making cooking utensils and boilers. Good conductor of heat. b) For making electric wires. Good conductor of electricity.
8.
How do metals react with oxygen? Metals react with oxygen of air to form their respective oxides
→ 2Na 2 O 4 Na + O 2 → 2MgO 2 Mg + O 2 → 2Fe 2 O 3 4 Fe + 3O 2 9.
What happens when? a) Sodium is exposed to air. When a piece of sodium is cut and placed exposed to air, the shining surface of the metal becomes dull and becomes powder of sodium carbonate. 4Na + O 2 2Na 2 O; 2Na 2 O + CO 2 → Na 2 CO 3 b) Sodium is burnt in excess of oxygen. When sodium burns in excess of oxygen, it produces sodium peroxide
→ Na 2 O 2 2Na + O 2 c) A piece of magnesium ribbon is burnt in air. It burns brightly in air forming magnesium oxide. A small amount of magnesium nitride is also formed due to high temperature.
→ 2MgO 2 Mg + O2 d) A foil of copper is burnt in air. Heat
When a foil of copper is heated in a flame, a black layer of copper oxide is formed.
→ 2CuO 2Cu + O 2 Heat
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e) Aluminium powder is heated in sparklers. Aluminium powder of a sparkler, crackers and fireworks burn with a white light.
→ 2Al 2 O 3 4Al + 3O 2 10.
What is meant by rust? Write its chemical formula. Rust is hydrated oxide of iron formed on iron articles when they are exposed to moist air for a long time. The formula of rust is Fe 2 O 3 2H 2 O
11.
Give reason: a) Iron exposed to air rusts quickly during rainy season. Due to the presence of excess water vapour. b) Iron nail kept in a closed jar containing calcium chloride does not rust. As air is dry because of the presence of anhydrous calcium chloride. c) Tin is used to coat the inner walls of brass and copper utensils. To avoid corrosion or rusting.
12.
What are the methods of preventing rusting of iron? Iron articles can be coated with zinc or chromium. By painting the iron articles. By heating and dipping in molten coal tar.
13.
Why is iron grill painted frequently? To prevent rusting of iron.
14.
Give reason: Metallic articles which are exposed to air over long period of time lose their lustre. Due to the formation of oxide, hydroxide and carbonate layers.
15.
A student has been collecting silver coins and copper coins. One day she observes a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the names of black and green coatings. The phenomenon is called corrosion. Silver gets tarnished when exposed to atmosphere which forms a black coating of silver oxide. Copper forms a green deposit on its surface when exposed to moist air. The green coating is copper sulphate.
16.
Why is sodium preserved in kerosene? Sodium is highly reactive in air. It reacts with air gradually forming sodium carbonate. It catches fire and burns when exposed to air. It does not react with kerosene so sodium is preserved in kerosene.
17.
Petrol is not selected for preserving sodium or potassium metal. Why? Petrol evaporates easily and is costly hence kerosene is used.
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Give reason: During burning of magnesium not only magnesium oxide is formed but also magnesium nitride is formed. Due to high temperature the triple bond between nitrogen atoms is broken and a small quantity of magnesium nitride is formed.
19.
Give reason: Magnesium ribbon should not be kept near bottles containing volatile chemicals. Magnesium is a reactive metal therefore it should not be kept near bottles containing volatile chemicals.
20.
Why do gold ornaments look new even after several years of use? Gold does not corrode when exposed to atmosphere. It is a highly unreactive metal and is unaffected by air, water vapour and other gases in atmosphere.
21.
How do metals react with nitrogen? Metals react with nitrogen forming respective nitrides at high temperature. Magnesium reacts with nitrogen to form magnesium nitride.
→ Mg 3 N 2 3Mg + N 2 Heat
22.
How do metals react with hydrogen? Metals react with hydrogen to form respective hydrides. Calcium reacts with hydrogen to form calcium hydride.
→ CaH 2 Ca + H 2 Heat
23.
How do metals react with chlorine? Metals react with chlorine to form respective chlorides. Aluminium reacts with chlorine to form aluminium chloride.
→ 2AlCl 3 2Al + 3Cl 2 Heat
24.
What happens when heated aluminium powder is sprinkled into a jar of chlorine gas? As heated aluminium powder comes in contact with chlorine, bright flashes are seen forming aluminium chloride.
→ 2AlCl 3 2Al + 3Cl 2 Heat
25.
How do metals react with sulphur? Metals react with sulphur forming respective sulphides. Iron reacts with sulphur forming ferrous sulphide.
→ FeS Fe + S How do metals react with water? Heat
26.
Metals react with water differently. a) Sodium reacts vigorously with water giving sodium hydroxide and hydrogen.
2Na + 2H 2 O → 2NaOH + H 2 ↑ Girish.N, Bengaluru
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b) Magnesium reacts with boiling water to form magnesium oxide & hydrogen.
→ Mg(OH) 2 + H 2 ↑ Mg + 2H 2 O c) Zinc reacts with steam forming zinc oxide & hydrogen.
→ ZnO + H 2 ↑ Zn + H 2 O d) Magnesium reacts with steam to form magnesium oxide & hydrogen.
→ MgO + H 2 Mg + H 2 O e) Red hot iron reacts with steam forming iron oxide & hydrogen,
→ Fe3O4 + 4H 2 ↑ 3 Fe + 4H2O Heat
27.
Choose a metal out the following which reacts with hot water but not cold water: Sodium, Magnesium & Iron. Mention the products formed during the reaction. Magnesium reacts with hot water but not with cold water. The products formed are magnesium hydroxide and hydrogen.
→ Mg(OH) 2 + H 2 ↑ Mg + 2H 2 O 28.
Of the three metals X, Y and Z. X reacts with cold water, Y reacts with hot water and Z reacts with steam only. Identify X, Y and Z and also arrange them in the order of increasing reactivity. X is sodium. Y is Magnesium and Z can be iron, Aluminium or zinc. Increasing order of reactivity is sodium, magnesium and iron.
29.
What happens when a piece of sodium is gently dropped into a trough of water? Sodium floats on water with a hissing noise forming sodium hydroxide & hydrogen.
2Na + 2H 2 O → 2NaOH + H 2 ↑ 30.
5 grams of iron filings is taken in hard glass tube in a horizontal position. One end of horizontal tube is connected to a boiler filled with water and other end of the horizontal tube is connected to a delivery tube fixed to a balloon. i) What happens during the experiment? Water boils producing steam. Steam reacts with iron filings forming hydrogen gas. Hydrogen gas fills in the balloon. ii) Name the gas produced Hydrogen iii) How do you know that the gas is hydrogen? When the mouth of the balloon is tied and released, the balloon goes up and sticks to the roof as hydrogen is the lightest gas.
31.
In the figure of Lane process of manufacture of hydrogen, identify the parts labelled A and B. Part A is water and Part B is iron filings.
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Briefly explain the Lane process of manufacture of hydrogen. In a hard glass borosilicate tube with both sides open, take 5g of iron filings in a horizontal position and arrange the apparatus as shown in the figure. When water is boiled in the jar containing water, steam is produced which passes through the horizontal tube containing iron filings. Iron filings react with steam forming hydrogen.
33.
Name the products of electrolytic decomposition of acidified water. Hydrogen and oxygen
34.
How do metals react with dilute hydrochloric acid? Metals react with dilute hydrochloric acid to produce respective metallic chlorides and hydrogen. a) Magnesium reacts readily to form magnesium chloride.
→ MgCl 2 + H 2 ↑ Mg + 2HCl b) Zinc reacts readily to form zinc chloride.
→ ZnCl 2 + H 2 ↑ Zn + 2HCl c) Iron reacts slowly to form iron chloride. → 2FeCl 3 + 3H 2 ↑ 2Fe + 6HCl 35.
What happens when concentrated hydrochloric acid is poured into a test tube containing zinc granules? Zinc reacts with concentrated hydrochloric acid vigorously forming and the chemicals spill out of the test tube.
36.
In the diagram identify the parts labelled A and B. Part A is Zinc granules and concentrated hydrochloric acid. Part B is Soap bubbles filled with hydrogen.
37.
In a test tube about 10g of zinc granules is taken. Dilute hydrochloric acid is added to the test tube up to half its volume. A one holed cork is fixed to the test tube. A rubber tube is taken out of the test tube and passed through a trough containing soap solution. i) What do you observe? Zinc reacts with dilute hydrochloric acid forming zinc chloride and hydrogen gas. As hydrogen gas pass through soap solution, soap bubbles filled with hydrogen rises up. ii) Write the chemical equation for the reaction.
→ ZnCl 2 + H 2 ↑ Zn + 2HCl iii) What happens when you ignite the soap bubbles with a match stick? When the soap bubbles are ignited with a burning match stick, it makes a pop sound as hydrogen is a combustible gas.
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Give reason: a) Magnesium reacts more vigorously with hydrochloric acid than zinc or copper. The reactivity of magnesium is higher than that of zinc. Hence it reacts with hydrochloric acid more vigorously. b) Iron takes more time to react with dilute hydrochloric acid than magnesium and zinc As iron has lowest reactivity when compare to magnesium and zinc.
39.
Sodium displaces hydrogen from dilute acids violently but copper does not displace hydrogen from dilute acids. Why? Sodium is highly reactive than copper. Hence reaction with sodium reacts violently then that of copper.
40.
How do metals react with dilute sulphuric acid? Metals displace hydrogen from dilute sulphuric acid and form respective metallic sulphates.
→ ZnSO 4 + H 2 ↑ Zn + H 2 SO 4 41.
Write the equations of chemical reactions taking place between a) Magnesium and dilute sulphuric acid
→ MgSO 4 + H 2 ↑ Mg + H 2 SO 4 b) Iron and dilute sulphuric acid
→ FeSO 4 + H 2 ↑ Fe + H 2 SO 4 42.
Write the reaction between a) Copper and concentrated sulphuric acid. Heat Cu + 2H 2 SO 4 → CuSO 4 + SO 2 ↑ + 2H 2 O
61.
b) Zinc and concentrated sulphuric acid. Heat Zn +2H 2 SO 4 → ZnSO 4 + SO 2 ↑ + 2H 2 O
43.
How do metals react with nitric acid? a) Very dilute nitric acid reacts with very active metals like magnesium and zinc to give their metallic nitrates and hydrogen gas.
→ Zn(NO 3 ) 2 + H 2 ↑ Zn + 2HNO 3 → Mg(NO 3 ) 2 + H2↑ Mg + 2HNO 3 b) Moderately dilute nitric acidreacts with metals to give their nitrates and nitric oxide.
→ Cu(NO 3 ) 2 + 2NO + 4H 2 O 3Cu + 8HNO 3 c) Concentrated nitric acid reacts with metals on heating to give their nitrates, water and nitrogen dioxide.
→ Cu(NO 3 ) 2 + 2NO 2 + 2H 2 O Cu + 4HNO 3 44.
In the diagram identify the parts labelled A and B Part A is colourless nitric oxide gas.
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Part B is reddish brown fumes of nitrogen dioxide. In a test tube 10g of copper turnings is taken. Moderately concentrated nitric acid is added to it. i) Name the gas released. Nitric oxide ii) Name the gas formed at the mouth of the test tube? Nitric oxide cones in contact with oxygen and forms reddish brown nitrogen dioxide gas. ii) Write the chemical equation of the reaction.
→ 2NO 2 2NO + O 2 46.
What happens when gold ornament is heated with dilute nitric acid? The copper constituent of the ornament reacts with the acid forming greenish copper nitrate solution and reddish brown fumes of nitrogen dioxide. Gold remains unaffected.
47.
What happens when a iron nail or a piece of aluminium wire is dipped in concentrated nitric acid? Iron nail or aluminium wire does not react with concentrated nitric acid. It makes iron more passive.
48.
Give reason: Aluminium / Iron become passive when immersed in concentrated nitric acid. Since concentrated nitric acid is a powerful oxidising agent, it forms a protective oxide layer on the metal instantly.
49.
Name the gases produce in the following chemical reactions. a) Copper reacts with sulphuricacid. Sulphur dioxide b) Copper reacts with concentrated nitricacid. Nitrogen dioxide
50.
Give an example of displacement reaction of iron. OR What happens when an iron nail is immersed in? a) Copper sulphate solution When an iron nail is placed in copper sulphate solution, iron displaces copper from copper sulphate solution.
→ FeSO 4 + Cu ↓ Fe + CuSO 4 b) silver nitrate solution When an iron nail is placed in silver nitrate solution, iron displaces silver from silver nitrate solution,
→ Fe(NO 3 ) 2 + 2Ag ↓ Fe + AgNO 3 51.
Give reason: Iron displaces copper from copper sulphate solution.
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Iron is more reactive than copper. Hence it displaces copper from copper sulphate solution. In a solution of silver nitrate, a copper plate was dipped. After some time, silver from the solution was deposited on the copper plate. Which metal is more reactive – copper or silver? More reactive metal displaces a less reactive metal. Hence copper metal is more reactive.
53.
A solution of CuSO4 was kept in an iron pot. After a few days, the iron pot was found to have a number of holes in it. Write the equation that took place. Explain. Iron metal is more reactive than copper. The equation for the displacement is:
→ FeSO4 + Cu CuSO4 + Fe Iron displaces copper from copper sulphate solution. 54.
Which of the following pairs will give displacement reaction? a) NaCl solution and copper metal. b) MgCl2 solution and aluminium metal. c) FeSO 4 solution and silver metal. d) AgNO 3 solution and copper metal. Copper metal is more reactive than silver metal. So displacement reaction will take place.
55.
Give reason: Some metals are more reactive than others. Metals are electropositive and have tendency to donate electrons. Some elements give up their valence electrons and hence more reactive.
56.
Name some metals which do not displace hydrogen from dilute acids. Platinum, gold, silver, mercury & copper do not displace hydrogen from dilute acids.
57.
Which gas is always produced if a metal reacts with water or dilute acid? Hydrogen
58.
Given below are metals in order of reactivity. a) Which element is stored in kerosene? sodium b) Which element will react with cold water? Sodium, calcium c) Which element will react with steam but not cold water? Iron
59.
Name the metal which has been placed: a) At the bottom of the reactivity series Platinum b) At the top of the reactivity series Potassium
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c) Just below copper in the reactivity series Mercury
60.
→ 2Al2 O 3 + 4Fe ; CuSO 4 + Fe → FeSO4 + Cu ; 2Fe 2 O 3 + 4Al → Cu(NO 3 ) 2 + 2Ag AgNO 3 + Cu Observe the above chemical equations and arrange the metals in the reactions in their increasing order of reactivity. Iron, Copper & Silver
61.
What is an ore? The compound of a metal from which the metal can be extracted economically is called an ore.
62.
Name the ores of the following metals and their composition. Name of metal
Name of ore
composition
Aluminium
Bauxite (Oxide ore)
Al 2 O 3 2H 2 O
Iron
Haematite Magnetite(Oxide ore)
Fe 2 O 3 Fe 3 O 4
Native form
-
Cholcopyrites or copperpyrites (Sulphide ore)
CuFeS 2
Gold Platinum Copper
63.
Manganese
Pyrolusite (Oxide ore)
MnO 2
Chromium
Chromite
FeOCr 2 O 3
Magnesium
Magnesite (carbonate ore)
MgCO 3
Give reason: Gold occurs in native form. Gold is low in the reactivity series. It is least reactive or unreactive. Hence gold is found in free state.
64.
Define metallurgy. The technology of extraction of metals from their ores and refining them to required form is called metallurgy.
65.
Explain the following terms with reference to metallurgy. a) Gangue The unwanted impurities present in the ore are called gangue. b) Concentration of ore The process of removing the gangue particles to increase the percentage of desired component of the ore is called concentration of the ore. c) Roasting
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The process of heating the ore just below its melting point in the presence of air is called roasting. Ex: Zinc blende (ZnS) is roasted in the air to convert it into zinc oxide (ZnO).
d) Calcination The process of heating the ore just below its melting point in the absences of air with a purpose of driving away volatile matter like water and carbon dioxide is called calcination. Ex: Oxide ores containing water vapour are calcined. Carbonate ores calcined to drive away carbon dioxide. e) Flux The substance that is added to the ore before heating with a purpose of removing certain unwanted impurities which are not removed during concentration of ore is called flux. f) Slag The substance formed by the combination of impurities like sand is called slag. 66.
67.
Differentiate between roasting and calcination. Roasting
Calcination
The process of heating the ore just below its melting point in the presence of air
The process of heating the ore just below its melting point in the absences of air with a purpose of driving away volatile matter like water and carbon dioxide
What happens when? a) A cleaned iron plate or iron nail is kept in 10g of copper sulphate solution. After a few hours a coating of copper is seen on iron nail/plate. It is based on displacement reaction. b) A pinch of mercuric oxide is kept in a test tube. After some time a mirror of mercury on the cooler part of the test tube is formed. It is based on displacement reaction. c)A small crystal of silver nitrate is dissolved in distilled water and a drop of ammonium hydroxide & a pinch of glucose powder are added. A coating of silver on the inner walls of the test tube. Aldehyde group in glucose reduced silver nitrate to metallic silver.
68.
How is iron ore concentrated? The chief ore of iron is haematite. Haematite ore is concentrated by hydraulic washing. The crushed ore is washed with a stream of water, lighter gangue particles will be washed away and the heavy iron ore particles also with silica settles down during washing.
69.
Briefly explain the extraction of iron with chemical equations. Calcined iron ore is mixed with limestone and coke. The mixture is called charge. Charge is transferred to a blast furnace. A blast of hot air is sent through the charge. a) Coke present in the charge catches fire to form carbon dioxide with a large amount of heat.
→ 2CO C + O 2 b) Carbon dioxide gas formed reacts with more coke forming carbon monoxide.
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→ 2CO CO 2 + C c) Limestone decomposes to form calcium oxide and carbon dioxide. → CaO +CO 2 CaCO 3 d) Calcium oxide combines with silica present in the ore to form calcium silicate (slag) → CaSiO 3 CaO + SiO 2 e) At a temperature between 400 and 750oC, carbon monoxide reduces iron oxide to form iron metal. → 2Fe + 3CO 2 Fe 2 O 3 + 3CO The molten iron metal is collected at the bottom of the furnace is called cast or pig iron, 70.
What is charge? The mixture of haematite, lime stone and coke is called charge.
71.
State the role of lime stone in the extraction of iron from haematite. Or Why is lime stone added during the extraction of iron? Limestone reacts with the sand present as impurity in the ore forming calcium silicate which is taken out of the blast furnace as slag.
72.
What happens when lime stone is not added during the extraction of iron? If limestone is not added to charge during the extraction of iron, the blast furnace will get blocked.
73.
Why is flux used in the blast furnace? Flux in extraction of iron is limestone. Limestone reacts with the sand present as impurity in the ore forming calcium silicate which is taken out of the blast furnace as slag.
74.
What is the role of coke in the extraction of iron? Coke is a good reducing agent. It reduces iron oxide to iron. It is also a good fuel which supplies heat energy for the chemical reactions.
75.
Why is slag collected above molten iron? Slag is lighter than molten iron and collects above molten iron. Slag prevents oxidations of molten iron back into iron oxide.
76.
How is the slag obtained in the extraction of iron useful? Slag obtained in blast furnace is used as one of theraw materials of glass and cement.
77.
Mention the uses of cast iron. Cast iron is used for: a) Making stands for wooden benches and desks. b) Making dosa pan c) Making lid for covering manholes of sewage system. d) Making machinery parts.
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Name the impurities present in cast iron. How can these impurities be removed? Cast iron contains sulphur, phosphorous, silicon and carbon. The impurities present in the blast furnace can be removed by using Bessemer converter, open hearth process or electric furnace.
79.
Draw a neat diagram of the blast furnace used in the extraction of iron from haematite.
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Mention the uses of aluminium salts. a) Aluminium salts are used as mordant in textile industry (to bind the dye to the cloth). b) Potash alum is used to prevent bleeding from small cuts by coagulating the blood at the surface.
81.
What is a mordant?
82.
A mordant is a substance which helps to bind the dye to the cloth. What is alumina? Write its molecular formula. Alumina is chemically hydrated oxide of aluminium. Its formula is Al 2 O 3 .2H 2 O.
83.
Why is extraction of aluminium not commercially viable by using reducing agents like coke? OR Coke is used in the extraction of iron but not in the extraction of aluminium. Why? OR Aluminium cannot be extracted by heating bauxite and coke. Why? Oxygen of aluminium oxide cannot be easily taken away by reducing agents like coke.
84.
How is bauxite converted into alumina? Powdered bauxite is dissolved in hot sodium hydroxide solution to get a solution of sodium aluminate.
→ 2NaAlO 2 + H 2 O Al 2 O 3 + 2NaOH The gangue particles are filtered out. Carbon dioxide is passed through the filtrate to get a gel like precipitate of aluminium hydroxide.
→ 2Al(OH) 3 + Na 2 CO 3 2NaAlO 2 + CO 2 + 3H 2 O Sodium carbonate is separated by filtration. The precipitate of aluminium hydroxide is heated to get pure alumina.
→ Al 2 O 3 + 3H 2 O 2Al(OH) 3 85.
Why is pure alumina needed for the extraction of aluminium? For electrolysis of we need pure alumina. Hence bauxite is converted into alumina by chemical process.
86.
What is the difficulty in obtaining aluminium from alumina?
87.
Pure alumina melts at 2323K. At this temperature, aluminium vapourises and there will be considerable loss. It consumes more energy and also molten aluminium is not a very good conductor of electricity. What is the role of molten cryolite in the extraction of aluminium?
88.
When pure alumina is mixed with molten cryolite, it forms an electrolyte at 1223K. Molten cryolite also acts as a solvent for alumina. What is cryolite? Write its chemical formula. Cryolite is chemically sodium aluminium fluoride. Its molecular formula is Na 3 AlF 6 .
89.
Briefly explain the extraction of aluminium from alumina with chemical equations.
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Aluminium oxide dissolved in molten cryolite is taken in a chamber with gently sloped base.The inner wall is made of carbon lining. Graphite rods are introduced in the electrolyte bath. The carbon lining is connected to the cathode and graphite rods are connected to the anode. A strong source of direct current is passed. 90.
Molten aluminium collects at the lining and flows out of the gently sloped base. Name the process by which the refining of aluminium is done. Name the material used for the process. Aluminium is refined by electrolytic refining. Carbon lining acts as the cathode and the graphite rods act as anode.
91.
Draw a neat diagram of the electrolytic tank used in the extraction of aluminium from alumina.
92.
The following is a sketch of an electrolytic cell used in the extraction of aluminium: a) What is the substance of which the electrodes A and B are made? A is made of carbon, B is made of graphite. b) At which electrode (A or B) is the aluminium formed? Aluminium is formed at cathode or A c) What are the two aluminium compounds in the electrolyte C? Molten cryolite and alumina
93.
Mention the methods of obtaining ultra pure metal. a) Fractional crystallization or zone refining. b) Vacuum melting
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c) Distillation d) Chemical vapour deposition e) Liquation process 94.
What is meant by liquation process?
95.
Liquation is a process of obtaining ultra pure metal. It is based on the principle that metals are readily fusible where as the impurities are infusible at the temperature at which the metals fuse. What is meant by zone refining or fractional crystallization? Zone refining is a technique of obtaining ultra pure metal. It is based on the principle of differences in solubility of impurities in liquid and solid states of the metal.
96.
Explain the process of zone refining. Name one metal refined by this method. The apparatus used for zone refining consists of a circular heater fitted around the rod of impure metal at one end. The circular heater is slowly moved to the other end. At the heated zone, the rod melts and as the heater passes on, pure metal crystallizes and impurities insoluble in solid metal passes into the adjacent molten part. A metal refined by zone refining is germanium.
97.
What is electrolytic refining? Electrolytic refining is a technique of ultra refining of metal. In this method, impure metal is taken as anode and pure metal are taken as cathode. Electric current is passed through the electrolyte to obtain pure metal at the cathode.
98.
Briefly explain the electrolytic refining of copper. Copper is purified by electrolytic refining. The apparatus consists of an electrolytic tank containing copper sulphate solution as electrolyte. A set of thick blocks of impure copper is made anode (connected to the positive terminal of the battery) and a set of pure copper plates is made as cathode (connected to the negative terminal of the battery). On passing direct current through the electrolyte, the positively charged copper ions from copper sulphate go to the cathode and gets deposited on cathode giving pure copper. The process continues. Impure anode becomes thinner and pure cathode becomes thicker. The impurities collect at the bottom.
99.
Draw a neat diagram of the apparatus used in the electrolytic refining of copper.
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100. What is an alloy? An alloy is a homogenous mixture of two or more metals or metal with a non-metal. Example: Brass is an alloy of two metals copper and zinc. Steel is an alloy of a metal iron and non-metal carbon. 101. How is an alloy formed? Alloysare prepared by mixing the various metals in their molten state and cool them to room temperature. Better quality can be made by mixing metals using ultrasonics. 102. Why are alloys made? Alloys give desired properties to the metal. It improves the properties of metals. 103. Give reason: Metals belonging to the same group form good alloys. As metals belonging to the same group in the periodic table have similarities in electronic configuration. 104. How are the properties of alloys different from those of metals? Copper is reddish and zinc is grayish in colour where as brass which is an alloy of copper and zinc is golden yellow in colour. Iron is a magnetic substance but stainless steel, an alloy of iron is non magnetic. 105. Mention the alloys of iron, their composition and uses. Alloy
Composition
Uses
Stainless steel
Iron, carbon, chromium, nickel
Making surgical instruments & utensils.
Invar steel
Iron, carbon, nickel
Used in precision measuring tapes
Nickel steel
Iron, carbon, nickel
making machinery parts
106. What property of stainless steel is used in making surgical instruments? Surgical steel is not attacked by mild chemicals easily and it does not corrode. 107. What property of invar steel is used in making pendulums and measuring tapes? Invar steel has the least co-efficient of linear expansion. 108. Mention the alloys of copper, their composition and uses. Alloy
Composition
Uses
Brass
Copper, zinc
Electrical contact parts, utensils and decorative articles
Bronze
Copper, tin
Statues, medals and utensils
109. Which metal is present both in brass and bronze? Copper 110. Mention the alloys of aluminium, their composition and uses.
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Alloy
Composition
Uses
Duralumin
Aluminium, copper, magnesium, manganese
Aeroplane body, railway & bus coaches
Alnico
Aluminium, nickel, iron, cobalt
Permanent magnets
111. Name the alloy used in the following a) Electrical appliances–Brass b) Surgical instruments– Stainless steel c) Measuring tapes/pendulums – Invar steel d) Permanent magnets – Alnico e) Aircraft construction – Duralumin 112. Why is 6% to 8% copper added to gold in making ornaments? Pure gold is very soft, it cannot be used to make artistic ornaments. To make it hard, improve the looks and colour, 6 to8% copper is added to ornamental gold. 113. Write a note on contributions of Indians to metallurgy. a) Romans used armour and cutlery made from Indian iron. b) Indian metallurgist Nagarjuna wrote the book ‘Rasaratnakara’ in 9th century BC which explained the preparation of various metallic compounds, the extraction and purification of metals. c) Indians were the first to develop the method of extracting zinc and using it in alloys. d) The famous iron pillar at New Delhi near Qutab Minar constructed by Vikramadithya about 1600 years ago has withstood the action of weather. 114. What are memory alloys? How are they useful? Certain alloys which regain their original shape when deformed are called memory alloys. Preparation of memory alloys saves energy of melting and recasting of used articles. Fill in the blanks: 1. An example of a liquid metal is Mercury/gallium. 2.
A metal which is soft is sodium.
3.
A metal which lacks ductility is sodium.
4.
A non-metal which is lustrous is graphite/iodine.
5. 6.
An example of a non-metal which is a good conductor of electricity is graphite. An example of a non-metal which is lustrous is iodine/graphite.
7.
Metals are electron donors.
8. 9.
Metals are electropositive. Non-metals are electron acceptors.
10. 11.
Non-metals are electronegative. Metals displace hydrogen from dilute acids.
12.
Magnesium librates hydrogen gas on reacting with hot boiling water.
13. 14.
Metals turn red litmus blue. Non-metals turn blue litmus red.
15.
Oxides of zinc and aluminium are called amphoteric oxides.
16.
A metal oxide which is amphoteric is zinc oxide or aluminium oxide.
17.
Ordinary aluminium strips are not attacked by water because of the presence of a layer of aluminium oxide on the surface of aluminium.
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18. 19.
An example of non-metallic oxide is carbon dioxide. Non-metallic oxide oxides are acidic.
20. 21.
An example of neutral oxide is nitrous oxide/carbon monoxide. The oxide that can form salt and water with a base as well as an acid is carbon monoxide.
22.
The formula of rust is Fe 2 O 3 2H 2 O.
23. 24.
Rusting is a process of oxidation. Corrosion of iron is called rusting.
25.
Iron exposed to air rusts rapidly in rainy season than in summer due to increase in humidity.
26. 27. 28.
Sodium is preserved in kerosene. The gas produced when steam is passed over red hot iron is Hydrogen. The metal that does not liberate hydrogen with dilute acids is copper.
29.
The metal that does not react with air is platinum/gold.
30. 31.
The metal that does not react with water is platinum/gold. The oxide of iron obtained in Lane process of manufacture of hydrogen is called ferric oxide or ferrosoferric oxide.
32. 33. 34.
The gas obtained with sodium reacts with water is hydrogen. If X is a metal, then litmus will turn red to blue. If X is a non-metal, then litmus will turn blue to red.
35.
The compound of a metal from which the metal can be extracted economically is called an ore.
36.
An example of a metal that occurs in native or elemental form is gold/platinum.
37. 38.
The metal extracted from bauxite is aluminium. The metal extracted from pyrolusite is chromium.
39.
The technology of extraction of metals from their ores and refining them to required form is called metallurgy.
40.
The unwanted impurities present in the ore are called gangue.
41.
The process of heating the ore just below its melting point in the presence of air is called roasting.
42.
The process of heating the ore just below its melting point in the absences of air is called calcination.
43.
The substance that is added to the ore before heating with a purpose of removing certain unwanted impurities is called flux.
44.
The substance formed by the combination of impurities like sand is called slag.
45. 46.
The metal which is referred to as poor man’s silver is aluminium. The 3rd most abundant element is aluminium.
47. 48.
The electrode at which aluminium metal is produced is cathode. The gas produced during the extraction of aluminium is oxygen.
49.
Oxygen gas is produced during the extractionof aluminium is produced at anode.
50.
Limestone is used as flux in extraction of iron.
51. 52.
CaSiO3 is known as slag in extraction of iron. The anode in the electrolytic refining of copper is impure copper plates.
53.
The cathode in the electrolytic refining of copper is pure copper plates.
54.
Goldsmiths mix a small quantity of copper to pure gold to make it hard.
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55.
Iron pillar near Qutab Minar in Delhi has not got rusted till now due to coating of Fe 3 O 4 on its surface.
56.
Brass is an alloy of copper and zinc.
57. 58.
Bronze is an alloy of copper and tin. The non metal present in stainless steel is carbon.
59.
Aluminium+ copper+ magnesium+ manganese is useful in making aircraft bodies.
60.
Ornamental gold is an alloy. *****
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Chapter 16: Electromagnetic Induction 1.
P16
Define e.m.f The energy required to maintain potential difference between the ends of a conductor is called electro motive force (e.m.f)
2.
State the SI unit of potential difference and emf. The SI unit of potential difference and emf is volt.
3.
Define electromagnetic induction. The phenomenon in which electro motive force (emf) is induced in the circuit when the magnetic field linked with a circuit changes is called electromagnetic induction.
4.
Explain Faraday experiment to illustrate the phenomenon of electromagnetic induction. Faraday wound a long copper wire on a cardboard cylinder. He wound twine between the turns and placed calico cloth between the layers. He moved a pole of bar magnet quickly into the coil. The deflection in the galvanometer indicated electric current in the coil. When the magnet was at rest inside the coil, no electricity was produced. When he pulled the magnet out of the coil, the galvanometer deflected in the opposite direction. The amount of deflection, increased with increase in the speed of the magnet. This experiment shows that magnetic field can produce electricity
5.
Give reason: In the experiment conducted by Faraday the induced electric current was not DC. The deflection in the galvanometer was to one side when the magnet was pushed in and the deflection was to opposite side when the magnet was taken out. Hence it was AC and not DC.
6.
What is a galvanometer? What is its use? Galvanometer is a device used to measure the electric current flowing through a conductor.
7.
What is induced current? The electric current produced in the circuit when magnetic field linked with a circuit changes is called induced current.
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Can a static magnet induce an e.m.f in a stationary coil of wire? Give reasons. No, when both coil and magnet are stationary, the magnetic field linked with the coil remains constant. Only when the magnetic field linked with the coil changes, current is produced.
9.
On what factors does the induced emf in the coil depend? Induced e.m.f in a coil increases with increase in: a) the number of turns of the coil, b) the strength of the magnetic field c) the speed with which the magnet or the coil moves d) area of the coil
10.
State Faraday’s first law of electro-magnetic induction. Whenever a magnetic field linked with a conductor changes, an induced e.m.f is generated in the conductor.
11.
State Faraday's second law of electromagnetic induction. The Magnitude of the induced e.m.f is directly proportional to the rate of change of magnetic field linking the conductor.
12.
State Fleming's right hand rule or Dynamo rule. Arrange the first three fingers of the right hand mutually perpendicular to each other; if the fore finger indicates the direction of magnetic field, the thumb in the direction of motion of the conductor, then the middle finger indicates the direction of the induced e.m.f
13.
What should be the angle between the thumb (main) finger and the central finger in Fleming’s rule? What does each finger indicate? The angle between the thumb and the central finger must be 90o. Fore finger indicates direction of magnetic field, thumb indicates direction of mechanical force / motion of conductor and the central finger indicates the direction of induced current or electric current.
14.
Mention the applications of electromagnetic induction. The three devices which work on the principle of electromagnetic induction are:
15.
a) A.C. and D.C. Dynamo b) What is a dynamo?
b) Transformer c) Induction coil
A dynamo is a device which converts mechanical energy into electrical energy. 16.
On what principle does a dynamo work? Dynamo works on the principle of electromagnetic induction.
17.
What is an AC dynamo? A dynamo that produces an alternating current is called AC dynamo.
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Briefly explain the construction and working of an AC Dynamo or generator. Construction: An AC dynamo or generator consists of an
insulated copper coil of many turns wound over a soft iron core. In the figure ABCD represents the insulated coil. The coil is placed between the pole pieces of a concave cylindrical magnet. The free ends of the copper wire are connected to two copper rings R 1 and R 2 . Two carbon brushes B 1 and B 2 touch the rings R 1 and R 2 . The brushes are connected to the external load L. Working: When the coil is made to rotate in clockwise direction, the magnetic field linked with the coil changes. This induces an electric current in the coil ABCD. During the first half of the rotation, the current flows along ABCD R 1 B 1 B 2 . During the second half of the rotation current is induced in the coil along DCBA R 2 B 2 B 1 . 19.
Draw a neat diagram of AC dynamo
20.
What an armature? The coil of insulated copper wire wound over a core of soft iron is called armature.
21.
How does the armature rotate in the following? a) Bicycle dynamo: The friction between moving tyre and the cylindrical head of the armature. b) Hydro-electric power station: Turbines rotate by the flow of water. c) Nuclear power reactor: Turbines rotate by the flow of steam. d) Windmills: Turbine rotate by the force of wind.
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What is the voltage and the frequency of the A.C source supplied to our homes and industries? The voltage range of domestic AC is 230 to 250 volts. The frequency of A.C source is 50 Hz or 50 cycles per second.
23.
Write the graphical representation of the alternating current.
24.
Mention the uses of alternating current. 1. Alternating current is used in domestic appliances like lamps, heaters, fans, ovens, radio etc. 2. It is used to produce required frequency of radio waves for radio and T.V transmission.
25.
3. It is used for RADAR and wireless communication. 4. It is used to produce ultrasonic waves used in industries, ultrasound scanning and SONAR. When is the magnitude of induced current maximum and minimum? Induced current is maximum when the plane of the coil is perpendicular to the plane of the coil. Induced current is minimum when the plane of the coil is parallel to the plane of the coil.
26.
What is a DC dynamo? A dynamo that produces a "direct current" is called DC dynamo.
27.
Briefly explain the construction and working of a DC Dynamo. Construction:
A DC dynamo consists of an insulated copper coil of many turns wound over a soft iron core. In the figure ABCD represent the insulate coil. The coil in placed between the pole pieces of concave cylindrical magnets. The free ends of the copper wire are connected to two half rings S1 and S2 called split ring. Two carbon brushes B1 and B2 touch split rings S1 and S2. The brushes are connected to the external load L. Working: When the coil is made to rotate in the clock wise direction, the magnetic field linked with the coil changes and induces an electric current in the coil ABCD. During the first half of the rotation, current flows along ABCD S 1 B 1 L B 2 . During the second half of the rotation of the coil, current is induced in the coil in the direction DCBA S 2 B 1 L B 2 . Since the current flows in the same direction in both the cycles this current is called direct current.
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28.
Draw a neat diagram of the DC Dynamo.
29.
Write the graphical representation of the direct current.
30.
Give reason: Split rings are used instead of slip rings to construct DC dynamo
174
Split rings make the current to flow in the same direction in the external circuit in both cycles. 31.
What should be the type of source of electric current to get electric current of constant magnitude? Direct current
32.
What is a commutator? The two half rings or split rings used to produce current in the same direction in a DC dynamo is called commutator.
33.
Give reason: A.C cannot be used for electrolysis. In electrolysis the ionisation of the electrolyte takes place where the positive and negative charges move towards opposite electrodes. But if we pass an alternating current the
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polarity of the electrodes will be continuously changing and the ions will not be attracted toward any particular electrode resulting in no ionisation. Hence electrolysis cannot take place with alternating current. 34.
Mention the differences between an AC dynamo and a DC dynamo. AC dynamo
35.
DC dynamo
1) The two ends of the coil are connected to two full rings of copper.
1) The two ends of the coil are connected to a commutator consisting of two half rings of copper.
2) The direction of current produced changes every half revolution.
2) The direction of current produced is same in both revolutions
What is an electric motor? An electric motor is a device that converts electric energy into mechanical energy.
36.
On what principle does an electric motor work? An electric motor utilizes the magnetic effect of current. It works on the principle that a conductor carrying current in a magnetic field experiences a mechanical force.
37.
State Fleming's left hand rule (motor rule). If the first three fingers of the left hand are held mutually perpendicular to each other such that the finger points in the direction of magnetic filed, the middle finger points in the direction of current, then the thumb points in the direction of mechanical force acting on the conductor.
38.
Explain the construction and working of a DC motor. Construction: An electric motor consists of a rectangular coil ABCD of insulated copper wire, wound on a soft iron core. The coil is mounted between the concave cylindrical poles of a permanent magnet in such a way that it can rotate between the poles N and S. The two ends of coil are connected to the two half rings S 1 and S 2 of a commutator. Two carbon brushes B 1 and B 2 are kept in contact with the split rings. The brushes are connected to the poles of a battery. Working: When electric current is passed through the coil in the direction ABCD, it sets up a magnetic field which is at right angles to the plane of the coil and a mechanical force acts on its limbs in opposing direction. Therefore the coil begins to rotate about its axis. During the first half of its rotation S 1 is in contact with B 2 . When S 2 comes in contact with B 1 electric current flows in the coil in DCBA, due to the magnetic momentum picked up b the coil during its rotation, it continues rotating. Thus a motor converts electrical energy into mechanical energy.
39.
Mention the devices that work on AC motor. Electric fans, electric mixer, electric grinder, washing machine work on AC source.
40.
Mention the differences between a dynamo & a motor. Dynamo 1) It converts mechanical energy into electric current.
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Motor 1) It converts electrical energy into mechanical energy.
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2) The coil is rotated in an electric field by an external force. It induces an electric current of the coil of the motor.
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2) Current is supplied to the coil resulting in the rotation of the coil of the motor.
What determines the frequency of AC produced in a generator? The number of rotations of the coil in one second determines the frequency of a AC generator.
42.
What is the effect on the magnitude of emf generated in an AC generator if the speed of rotation is increased? The magnitude of emf generated increases.
43.
Suggest two ways in an AC dynamo to produce a higher emf. a) By increasing the speed of rotation of coil b) By increasing the number of turns of the coil.
44.
In an AC dynamo, the speed at which the coil rotates is doubled. How would this affect a) the frequency of output voltage b) the maximum output voltage? a) Frequency is doubled b) Maximum output voltage is doubled.
45.
What energy conversion does take place in a dynamo when it is in use? Mechanical energy changes into electrical energy.
46.
A cyclist riding a cycle fitted with a dynamo to a tyre gets bright light in the bulb connected, when he pedals fast. Why? More magnetic lines of force change with respect to the coil, leading to more current being produced.
47.
Give reason: Stationary coil and stationary magnet cannot produce induced electric current. An emf is induced in the coil only when there is relative motion between the coil and the magnet.
48.
What is a transformer? A transformer is a device which is used for increasing or decreasing the AC voltage.
49.
On what principle does a transformer work? Transformer works on the principle of electromagnetic induction.
50.
Draw the symbolic representation of transformer.
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What is meant by mutual induction? The production of induced e.m.f in secondary coil due to change of current in a neighbouring primary coil is called mutual induction.
52.
What is a step up transformer?
53.
A transformer which increases the input voltage of an AC source is called a step up transformer. What is a step down transformer?
54.
A transformer which decreases the input voltage of the AC source is called step down transformer. What are primary and secondary coil in a transformer? The coil which is connected to input source is called primary coil. The coil which is connected to the output source is called secondary coil.
55.
Mention the factors on which the magnitude of the e.m.f induced in the transformer depends. 1) E.m.f in the primary coil 2) Number of turns in the primary coil 3) Number of turns in the secondary coil 4) The core material
56.
57.
58.
Write the relationship between the voltage and number of turns of primary and secondary coils of a transformer. 𝑒𝑚𝑓 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑢𝑟𝑛𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑢𝑟𝑛𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑝𝑟𝑖𝑚𝑎𝑟𝑦 𝑒𝑚𝑓 𝑖𝑛 𝑡ℎ𝑒 𝑝𝑟𝑖𝑚𝑎𝑟𝑦 𝑉𝑠 𝑁𝑠 = 𝑉𝑝 𝑁𝑝 Write the relationship between the Current and voltage in primary and secondary coils of a transformer. 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝒊𝒏 𝒕𝒉𝒆 𝒑𝒓𝒊𝒎𝒂𝒓𝒚 𝒆𝒎𝒇 𝒊𝒏 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅𝒂𝒓𝒚 = 𝑪𝒖𝒓𝒓𝒆𝒏𝒕 𝒊𝒏 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅𝒂𝒓𝒚 𝒆𝒎𝒇 𝒊𝒏 𝒕𝒉𝒆 𝒑𝒓𝒊𝒎𝒂𝒓𝒚 𝑽𝒔 𝑰𝒑 = 𝑽𝒑 𝑰𝒔 Mention the differences between step up & step down transformer. Step Up Transformer It is used to increase the AC voltage Primary coil has less number of turns then that of secondary coil Primary coil is thicker than that of the secondary coil The turns ratio Ns/Np > 1
59.
Step down Transformer It is used to decrease the AC voltage Primary coil has more number of turns than that of the secondary coil. Primary coil is thinner than that of the secondary coil The turns ratio Ns/Np < 1
If an AC source of 250 volts has to be stepped down to 10 volts, what should be the turns ratio of the primary coil and secondary coil?
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60.
A primary of 800 turns is connected to a 220V AC supply and the secondary has 8 turns. What will be the output voltage?
61.
A transformer is designed to work from 240V AC mains and to give a supply of 8V to ring a house-bell. The primary coil has 4800 turns. How many turns would you expect the secondary to have?
62.
The input and output voltages of a transformer are 220V and 44V respectively. Find the turns ratio.
63.
A transformer lowers e.m.f from 220 volts to 12 volts. If the number of turns in primary is 8800, how many turns are in secondary coil?
64.
Applying e.m.f to primary coil is 210V. If the number of turns in primary coil is 200 turns and that of in secondary is 20 turns then find the output voltage. Name the transformer.
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65.
179
If the primary of a transformer has 10 turns and the secondary of the transformer has 200 turns. What type of transformer is it? Express mathematical form related to this. It is a step up transformer.
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𝑉𝑠
𝑉𝑝
𝑁𝑠
= 𝑁𝑝
Name the device you would use to convert 200 V AC to 15V AC. Step down transformer.
67.
Name the parts labelled A and B. What is the material of this part? Is this transformer a step-up or step-down? Give reason. The part A is the primary coil. Part B is secondary coil The complete diagram is
The material is made from thin laminated sheets of soft iron.
68.
The diagram is of step-down transformer as the number of turns in the primary coil is more than that of the secondary. The secondary coil of a transformer in which the voltage is stepped down are usually made of thicker wire than primary. Why? The secondary coil is made of thicker wire to sustain larger electric current.
69.
What is an induction coil?
70.
Induction coil is a device which is used to obtain high D.C voltage from a low voltage DC source. Briefly explain the construction and working of an induction coil.
71.
Construction: An induction coil consists of a primary P having few turns of thick insulated copper wire wound over a soft iron core connected to a battery. It also has a secondary coil S of larger number turns wound over the primary coil. It has a make & break arrangement. Working: When a direct current flows in the primary, the core C gets magnetized and attracts the head of the switch M. The circuit breaks and current in the primary stops. C gets demagnetized and H comes back. The process repeats. During the make break of the circuit, large e.m.f is induced in the secondary coil. Draw a neat diagram of an induction coil and label the parts.
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State the functions of the following components in a dynamo /motor. a) Commutator: It is used to alter the direction of the current in me coil after every half rotation. b) Carbon brushes: it is used to supply a continuous current to the rotating coil through the commutator.
Fill in the blanks: 1.
When a current carrying conductor experiences highest mechanical force, the angle o between the direction of the conductor and the magnetic field is 90 .
2.
A device which converts mechanical energy into electricity is dynamo.
3.
The relation between the directions of electric current in magnetic field and the mechanical force acting on the conductor is given by Fleming’s left hand rule.
4.
In a conductor, a changing magnetic field linking a conductor induces electromagnetic force.
5.
The number of times direction of electric current changes when the armature of an AC dynamo makes five cycles is ten.
6.
A device which works on the principle that a current carrying conductor experiences a mechanical force in a magnetic field is electric motor.
7.
The SI unit of electro motive force is volt.
8.
The type of current required for depositing copper on cathode during electrolytic refining of copper is direct current.
9.
The current that changes its direction every half rotation is called Alternating current.
10. 11.
The type of electric current we get in our home is Alternating current. The frequency of alternating current we get in our home is 50Hz or 50 cycles.
12. 13.
The device which converts AC emf into DC voltage is called rectifier. The conversion of energy in a dynamo is mechanical energy to electrical energy.
14.
The frequency of the alternating current is the same as the frequency with which armature rotates.
15.
In a bicycle dynamo the friction between moving tyre and the cylindrical head of the armature make the armature rotate.
16.
In nuclear power reactor, the turbines rotate by the flow of steam.
17.
In AC dynamo, the magnitude of induced current is zero when the plane of the coil is parallel to the direction of magnetic field.
18.
In AC dynamo, the magnitude of induced current is maximum when the plane of the coil is perpendicular to the direction of magnetic field. The conversion of energy in a motor is electrical energy to mechanical energy.
19. 20. 21.
A transformer works on the principle of electromagnetic induction. The production of induced e.m.f in secondary coil due to change of current in a neighbouring primary coil is called mutual induction.
22.
A transformer which increases the input voltage of an AC source is called a step up transformer.
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23.
A transformer which decreases the input voltage of the AC source is called step down transformer.
24.
The coil which is connected to input source is called primary coil.
25.
The coil which is connected to the output source is called secondary coil.
26.
The magnitude of the emf induced in the secondary coil of a transformer depends on emf of primary / number of turns in primary / number of turns in the secondary / core material.
27. 28. 29.
NS is called turns ratio of the transformer. NP The number of turns in the primary of a step up transformer is less than that of the secondary. The number of turns in the primary of a step down transformer is more than that of the secondary.
30.
The device which is used to obtain high D.C voltage from a low voltage DC source is called induction coil.
31.
A, B and C are the three coils of conductor having different number of turns, wound around a soft iron ring as shown in the figure. Ends of coils B and C are connected to the galvanometers. The observation that can be made when ends of coil A are connected to an A.C. source is induced electric current is more in B than in C. *****
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P17
Chapter 17: Electronics 1.
What is electronics? Electronics is a field of physics and engineering dealing with the design and application of electronic devices.
2.
What are conductors? Give example. Substances that allow electric current to pass through them are called conductors. Example: Metals like copper, aluminium etc.
3.
What are insulators? Give example. Substances that do not allow electric current to pass through them are called insulators. Example: Plastic, rubber, wood, glass etc.
4.
Mention some electronic gadgets. Mobile phone, Laptop, tablet, computers, ultra sound scanner, X-ray etc.
5.
Which are the areas influenced by electronics? Electronics has influenced communications, medical science, laser technology, nano technology etc.
6.
What are semiconductors? Give example. Substances that have conductivity between that of conductors and insulators are called semiconductors. Example: Silicon, Germanium
7.
Distinguish between conductors and semiconductors. Conductors
8.
Insulators
Conduction is very high
Conduction is very low
Resistance is low
Resistance is higher than that of conductors
On heating resistance increases
On heating resistance decreases
Why is silicon an insulator at room temperature? Silicon has 4 valence electrons. Each atom forms 4 covalent bonds with its four neighbouring atoms. At room temperature, the electrons are bound to the atom and are not free. Hence semiconductors behave as insulators at room temperature.
9.
What is the reason for the conductivity of semiconductors? Semiconductors require a small amount of energy to break the covalent bond to set the electron free. Thus as the temperature increases, the number of electrons dissociated from their atoms increases. Thus semiconductors behave as conductors.
10.
Give reason: a) 14th group electrons are semiconductors except carbon. The valence electrons have a low energy that they cannot become free by absorbing normal energy from the surroundings.
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b) Silicon is more widely used than germanium. Silicon and germanium have same 4 valence electrons but silicon can be used at higher temperatures, cheaper and abundantly available. 11.
Explain the term ‘hole’ in electronics. When an electron is detached from the co-valent bond, it leaves a vacancy which behaves like a positive charge. This vacancy is called a hole.
12.
What is an intrinsic semiconductor or pure semiconductor? A semiconductor in which the number of holes and electrons are equal is called intrinsic or pure semiconductor.
13.
What is an extrinsic semiconductor or doped? A semiconductor whose conductivity is enhanced by addition of minute traces of impurities is called doped or extrinsic semiconductor.
14.
Write differences between intrinsic and extrinsic semiconductors. Intrinsic semiconductor
15.
Extrinsic semiconductor
They are crystals of pure elements like germanium or silicon.
They are formed by adding impurity atoms to a pure semiconductor.
The number of electrons is equal to number of holes
The number of electrons is not equal to number of holes
Electrical conductivity is less
Electrical conductivity is more
What are dopants? A dopant is a substance (impurity) that is added in traces to increase the conductivity of a semiconductor.
16.
What is meant by doping? The process of adding dopants to enhance the conductivity of semiconductors is called doping.
17.
How are extrinsic semiconductors classified? Extrinsic semiconductors are classified into two types depending upon the type of impurity added into a) n-type semiconductor b) p-type semiconductors.
18.
Explain the formation of an n-type semiconductor. When a small amount of a penta valant impurity like antimony, arsenic or phosphorous is added to a tetra valant element like Silicon or Germanium, four out of five electrons of each impurity atoms forms a bond with the nearest silicon atom. The fifth electron is free and acts as current carrier. The impurity added donates an electron to the semiconductor and becomes an n-type semiconductor. In an n-type semiconductor the majority charge carriers are electrons.
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Explain the formation of a p-type semiconductor. When a small amount of a trivalent impurity like Boron, Indium, Aluminium or Gallium is added to a tetra valant element like Silicon or Germanium, three electrons of each impurity atoms forms a bond with the nearest silicon atom. The fourth bond remains incomplete which has a deficiency of one electron. This results in the creation of a hole. This hole attracts electrons from the neighbouring covalent bond. The impurity atom accepts electron from the semiconductor and becomes n-type semiconductor. In an ntype semiconductor the majority charge carriers are holes.
20.
Distinguish between n-type and p-type semiconductor. n-type semiconductor
21.
p-type semiconductor
It is formed by adding a pentavalent impurity to a pure semiconductor.
It is formed by adding a trivalent impurity to a pure semiconductor.
Free electrons act as charge carrier
Holes act as charge carrier
Majority charge carriers are electrons
Majority charge carriers are holes
What is a semiconductor diode or junction diode? A diode is a single crystal of semiconducting material which is doped one side with a donor impurity and the other side with acceptor impurity.
22.
What is a p-n junction? The junction that is obtained when a p-type semiconductor and an n-type semiconductor are kept in contact is called p-n junction.
23.
What is meant by junction potential? The potential difference that is established due to the diffusion of electrons and holes across the boundary in the p-n junction is called junction voltage. The junction potential is 0.7v for Silicon and 0.3v for Germanium.
24.
What is meant by depletion region? The thin region around the junction containing immobile positive and negative charges is called depletion region.
25.
When is a p-n junction said to be biased? When an external source of e.m.f is connected to a p-n junction, it is said to be biased.
26.
What is bias voltage? The external voltage applied to make p-n junction biased is called bias voltage.
27.
When is a p-n junction said to be forward biased or what is meant by forward biasing of p-n junction? How does it affect resistance? When the positive terminal of a cell is connected to p-side and negative terminal to the n-side of a p-n junction then it is said to be forward biased. It offers low resistance.
28.
Why does a forward biased diode offer low resistance?
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The external voltage over comes the junction potential and provides an easy path for the flow of charges across the junction. Hence it offers low resistance. When is a p-n junction said to be reverse biased or what is meant by reverse biasing of p-n junction? How does it affect resistance? When the positive terminal of a cell is connected to n-side and negative terminal to the pside of a p-n junction then it is said to be reverse biased. It offers high resistance.
30.
Why does a reversed biased diode offer high resistance? The charge carriers are repelled from the junction and no current flows through the junction. Thus the diode offers a high resistance.
31.
Why is there a small flow current during reverse bias? In reverse bias there is a small flow of current due to minority charge carries electrons in p region and holes in n region.
32.
In the circuit given along side D – diode, A – Anode, C – Cathode, B – Battery, K – Plug key, L- Lamp. Answer the following questions: a) Does the lamp glow when the +ve terminal of battery is connected to A and –ve terminal is connected to C? The lamp glows as it is forward biased. b) Does the lamp glow when the +ve terminal of battery is connected to C and –ve terminal is connected to A? The lamp does not glow as it is reverse biased.
33.
34.
Distinguish between forward biasing and reverse biasing. Forward biasing
Reverse biasing
The positive terminal of the battery is connected to p-side and negative terminal is connected to n-side of a p-n junction
The positive terminal of the battery is connected to n-side and negative terminal is connected to p-side of a p-n junction
It offers low resistance
It offers high resistance
What is a rectifier? A rectifier is a device that allows current to pass through in one direction.
35.
Why is a diode called as rectifier? Diode allows current to pass only when it is forward biased when AC voltage is applied across a diode. This property is used to rectify AC voltage. Hence a diode is called as rectifier.
36.
Name the types of rectifier.
37.
The two types of rectifier are: a) Half wave rectifier b) Full wave rectifier. Write the circuit symbol of a diode.
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Mention the characteristics of a diode. a) Diode has a p-type semiconductor at one end and a n-type semiconductor on the other end. b) It can be biased by connecting to an external source of e.m.f c) It may be forward biased or reverse biased. d) It allows current to pass through in one direction only.
39.
Mention the applications of a diode. a) Diode is used to convert A.C into D.C. b) They are used in voltage regulation systems. c) They are used in logic circuits which are used in computers.
40.
Mention the different types of diodes and one use of each. a) Light Emitting Diode (LED): They are used in lighting, display units of electric and electronic devices. b) Zener diode: It is used in voltage stabilizers. c) Photodiode: It is used in light sensitive semiconductors. d) Laser diode: It is used in fiber optical fibre communications.
41.
What is a transistor? Name its three regions. Transistor is the short form of transfer resistor. It is a device having three terminal semiconductor. A transistor has two ends regions called emitter and collector. The middle is called base.
42.
Write the functions of the tree regions of a transistor. a) Emitter: It is of moderate size and heavily doped. It emits large number of majority carriers for the flow of current through the transistor. b) Base: It is the central region of the transistor. It is very thin and lightly doped. It regulates the flow of charges from emitter to collector. c) Collector: It is moderately doped and larger in size compared to emitter. It collects a major portion of majority carriers supplied by the emitter.
43.
Name the types of transistor. a) Bipolar Junction Transistor (BJT) b) Field Effect Transistor (FET) c) Metal Oxide Semiconductor Field Effect Transistor (MOSFET) d) Junction Effect Transistor (JET)
44.
Write about the biasing of a transistor. Emitter base junction is forward biased while collector base junction is reverse biased.
45.
Write the principle of a transistor or amplifier.
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A small change in the input signal (voltage) results a large change in the output signal (voltage).
46.
Draw the circuit diagram of a npn transistor amplifier or common emitter amplifier.
47.
Draw the circuit diagram of pnp transistor amplifier.
48.
Distinguish between npn and pnp transistor. npn Transistor
pnp transistor
It is formed by sandwiching one p-type region between two n-type regions
It is formed by sandwiching one n-type region between two p-type regions
The voltage between the Base and Emitter is positive at the Base and negative at the Emitter.
The voltage between the Base and Emitter is negative at the Base and positive at the Emitter
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Mention the applications of transistor. a) Transistor is used in amplifier.
50.
b) It is used in oscillator. c) It is used in switching circuits. What is an oscillator? Oscillator is a device to produce electric oscillations of a desired frequency.
51.
What is meant by superconductivity? The property by which certain materials show almost zero resistance at a very low temperature is called superconductivity. Ex: The resistance of mercury drops abruptly to zero at 4.2K
52.
What are superconductors? Give example. The materials which show property of superconductivity are called superconductors. Example: Mercury, oxide of compound of Lanthanum, Barium and copper.
53.
What is critical temperature? The temperature below which material becomes superconductor is called critical temperature.
54.
What is the most important feature of a superconductor? The most important feature of a superconductor is that once current is setup in a superconductor ring, it will continue indefinitely even if the battery connected is switched off.
55.
Mention the uses of superconductors. a) Superconductors are used in powerful electromagnets. b) High temperature super conductors are used in microwave devices. c) Superconductor magnets are used in Magnetic Resonance Imaging (MRI)
Fill in the blanks: 1. Silicon is a 14th group element. 2.
Silicon has 4 valance electrons.
3. 4.
Pure semiconductors are insulators at room temperature. When an electron is detached from the covalent bond, it creates a hole/vacancy.
5.
A hole behaves as a positive charge.
6.
The total current in the semiconductor is the sum of electric current due to flow of electrons and the flow of holes.
7.
In a pure/intrinsic semiconductor the number of electrons and holes are always equal.
8.
The impurities added to pure semiconductor to enhance the conductivity are called dopants.
9.
Dopants are added to pure semiconductors to enhance their conductivity.
10. 11.
The process of adding impurities to a pure semiconductor is called doping. An n-type semiconductor is formed by adding pentavalent impurity.
12.
An example of a pentavalent impurity is arsenic/antimony/phosphorous.
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13. 14.
Pentavalent impurity is called donor impurity. A p-type semiconductor is formed by adding trivalent impurity.
15. 16.
Trivalent impurity is called acceptor impurity. An example of a trivalent impurity is boron/indium/gallium/aluminium.
17.
In an n-type semiconductor majority charge carriers are electrons.
18.
In a p-type semiconductor majority charge carriers are holes.
19. 20.
A single crystal of semiconducting material which is doped one side with a donor impurity and the other side with acceptor impurity is called p-n junction or semiconductor diode. The junction potential is 0.7v for Silicon.
21.
The junction potential is 0.3v for Germanium.
22.
The thin region around the junction containing immobile positive and negative charges is called depletion region.
23. 24.
The process of connecting an external source of e.m.f to a p-n junction is called biasing. The external voltage applied to make p-n junction biased is called bias voltage.
25.
A forward biased p-n junction offers low resistance.
26. 27.
A reversed biased p-n junction offers high resistance. P-N junction diode allows current to pass in one direction only.
28. 29.
A device which allows current to pass in one direction only is called rectifier. The arrow mark in the circuit symbol of a diode represents conventional flow of current.
30. 31.
The electronic component used to convert A.C. to D.C. is diode. The electronic component used in voltage regulating system is diode.
32.
The type of diode used in voltage stabilizers is Zener diode.
33.
The type of diode used in display units of electric & electronic devices is Light Emitting Diode.
34. 35.
The short form of transfer resistor is transistor. In a transistor, the region which is heavily doped is emitter.
36.
In a transistor, the region which is lightly doped is base.
37.
In a transistor, emitter-base junction is forward biased.
38.
In a transistor, collector-base junction is reverse biased.
39.
A small change in input signal of a transistor results in a large change in output signal.
40.
The correct relation between current in emitter (IE ), current in base (IB ) and current in collector (IC ) is I E = IB + I C .
41.
The device used to produce electric oscillations of desired frequency is called oscillator.
42.
The property by which certain materials show almost zero resistance at a very low temperature is called superconductivity.
43.
The resistance of mercury drops abruptly to zero at 4.2K.
44.
The material which shows property of superconductivity is called superconductors.
45.
The temperature below which material becomes superconductor is called critical temperature. The highest temperature at which a material behaves as superconductor is about 125K.
46. 47.
The scientist from Indian Institute of Science, Bangalore who has done a remarkable work in the field of superconductivity is Professor C.N.R.Rao. *****
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Chapter 18: Behaviour of Gases
C18
1. Mention the features of gases. a) Gases are highly compressible. b) Gases exert pressure equally in all directions. c) Gases mix evenly in all proportions without any mechanical aid. d) Gases are least dense than other two states of matter. 2.
What happens when a balloon with little air is tied to the mouth of a bottle with hot water? Why? The balloon increases in size because temperature increases kinetic energy of gas molecules of balloon. This increases the random movement of gas molecules. Hence the volume increases gradually.
3.
What is meant by absolute zero temperature? o
The temperature -273 C is called absolute zero or zero Kelvin. 4.
State Charles’s law. “At constant pressure, the volume of a fixed mass of a gas is directly proportional to its absolute temperature (Kelvin)”.
5.
Write the mathematical form of Charles’s law. V ∝ T or V= KT
6.
Derive Charles’s law equation If T 1 is initial temperature in Kelvin, V 1 is the initial volume in litres, T 2 is the final temperature and V 2 is the final volume then According to Charles law V 1 = K T 1 or
V1 = K ...........(1) T1
Similarly V 2 = KT 2 or
V2 = K ...........(2) T2 V T1
1 From equation (1) and (2) we get =
7.
8.
V2 = K T2
What happens to the volume when the temperature is doubled according to Charles’s law? If the temperature is doubled, the volume would also be doubled. What happens to the volume when the temperature is reduced to one-half according to Charles’s law? If the temperature is reduced to one-half, the volume would also be reduced to one-half.
9.
What is the relationship between volume and temperature of gases when pressure is kept constant? Volume of a fixed mass of gas is directly proportional to its absolute temperature.
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Give reason: a) Soda bottles are often labelled “store in cool and dry place”. The carbon dioxide filled in soda bottles on exposure to heat, expands because the gas inside the bottle expands as temperature rises. b) Balloons pops out during hot summer more frequently than in winter. As the temperature increases in summer, the volume of the gas filled in balloon also increases which makes the balloons to pop out. c) During winter football filled with air reduces to its original size when taken outdoors. When football is taken out, its temperature decreases so the volume to gas filled also decreases.
11.
Why are the air bubbles smaller in size in lower layers but grows bigger as they rise up when water is boiled? Lower layers of water exert a lot of pressure on air bubbles. Hence they are smaller in size. But the pressure decreases as bubbles rise to the top. Hence they grow bigger.
12.
State Boyle’s law. “At constant temperature, the volume of a given mass of dry gas is inversely proportional to its pressure”.
13.
Write the mathematical expression of Boyle’s law. If V is the volume of a certain mass of gas, under pressure P at constant temperature then according to Boyle’s law,
Vα
1 P
V =K x
14.
PV = K
1 P
Give reason: When you exert pressure on air pillow, its size gets reduced. The volume of air filled in the air pillow decreases as we increase the pressure.
15.
How are pressure, volume and mass of a gas related? The product of the volume and pressure of a given mass of dry gas is a constant.
16.
If P 1 is the initial pressure, V 1 is the initial volume, P 2 is the final volume and V 2 is the final volume of a gas. Write the he relation between them. According to Boyle’s law P 1 V 1 = P 2 V 2 = constant
17.
Give reasons: a) Deep sea fishes die when suddenly brought to surface. The pressure at the bottom of the sea is more, but the pressure at the surface is less. So due to low pressure the fish dies.
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b) Scuba diver’s life is under threat when they suddenly come to the surface quickly. As a diver goes deeper underwater, that pressure begins to increase. With the increase in pressure volume decreases, nitrogen gas begins absorbing into the diver's blood. When the diver begins his ascent, these gas molecules begin to expand back to their normal volume. With a slow ascent, or through the use of a depressurization chamber, those gasses can work their way back out of the bloodstream as they return to their normal volume. c) Balloons pop when squeezed. When a balloon is squeezed, the pressure increases. So it pops. d) We feel uneasy pain in the ears during take off and landing of aeroplanes. When the aeroplane takes off or lands, there is imbalance in pressure inside and outside of eardrum. 18.
Mention some applications of Boyle’s law in our daily life. a) Deep sea fishes die when suddenly brought to surface due to low pressure. b) Scuba diver’s life is under threat when they suddenly come to surface quickly. c) It is used in daily life situations like breathing, filling cheeks with air, filling air to vehicle tyres. d) We feel pain in the ears when in an aeroplane during take off or landing.
19.
What is meant by diffusion? The random movement of gaseous molecules from the region of higher concentration to the region of lower concentration is known as diffusion.
20.
Give reason: a) Burning of kerosene does not produce much smell but when the burning ceases, it produces strong smell. When kerosene is burnt, only few molecules diffuse with air after combustion. But when the burning ceases the unburnt hot vapours of kerosene enters into air and strong smell is got. b) Smell of hot food reaches faster then that of cold food. Smell of hot food reaches faster because rate of diffusion is faster. Cold food diffuses slowly.
21.
Observe the experiment and answer the questions. Take a glass tube. Keep a cotton plug dipped in concentrated hydrochloric acid at one end of the glass tube and cotton plug dipped in liquid ammonia at the other end. a) What are the dense white fumes formed? The dense white fumes are of ammonium chloride NH4Cl. b) Why is the dense white fumes seen near the HCl end?
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As HCl gas is denser than ammonia gas they diffuse slowly. Lighter ammonia vapours move with more velocity and both gases react and produce dense white fumes of NH4Cl near the HCl cotton plug end. 22.
When does diffusion of gases takes place? Diffusion of gases takes place when the gases do not react with one another.
23.
What is rate of diffusion? The rate of diffusion of a gas is the volume of gas diffusing per unit time.
24.
State Graham’s law of diffusion.
25.
“The rate of diffusion of a gas is inversely proportional to the square root of its density”. Write the mathematical form of Graham’s law of diffusion.
rα
26.
1 d
d
or k= r d
Write the relationship between diffusion and mass.
r =K
1 d
(at const an t temperature)
But density = = ∴r
27.
1
or = r K
mass(m) volume(v)
K v = or r k m m v
What is the relationship between rate of diffusion and mass of gas? Rate of diffusion is inversely proportional to mass of gas.
28.
29.
Name the gas responsible for Bhopal gas tragedy. Methyl Isocyanate which is produced by the chemical combination of phosgene gas and methyl cyanide. Give reason: a) During the Bhopal gas tragedy, cockroaches, ants and mosquitoes survived. Methyl Isocyanate is a gas denser than air. Hence it was unable diffuse in the crevices. So these animals survived. b) When there is L.P.G leakage, one is advised to open all doors and windows. When the doors and windows are opened the rate of diffusion of the LPG with air molecules is faster. Hence any damage by explosion can be prevented.
30.
5
2 litres of gas enclosed in a vessel at 2x10 pa pressure and allowed to expand about 4 litres under constant temperature. What would be the final pressure?
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5 If the product of pressure and volume of a gas is 15x10 and if the pressure is 5 1.5x10 pa. Find the volume in litres. (At constant temperature)
32.
5 If the pressure of a gas is 2.5x10 Pa and the volume of a gas is 6 litres then find the constant. (At constant temperature)
33.
5 If the volume and the product of a gas are 5 and 15x10 find the pressure of the gas. (At constant temperature)
34.
The volume of the gas found to be at a pressure of 2500pa when the pressure was decreased by 500pa the gas occupied a volume of 2400 litres. Calculate the initial volume occupied by the gas before the change was done at constant temperature.
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About 6 litres of oxygen gas is collected at 300K. If for a particular use, the volume has to be reduced to
1 of its original volume, find the temperature to which the gas 3
has to be cooled? [Pressure is kept constant]
36.
A balloon has a volume of 2500ml on a day when the temperature is 30°C. If the temperature at night falls to 10°C, what will be the volume of the balloon if the pressure remains constant?
37.
When 50 litres of oxygen at 20°C is compressed to 5 litres, what must the new temperature be to maintain constant pressure?
Fill in the blanks: 1.
Under constant pressure degree rise in temperature, the volume of gas increases by
2.
of the original volume at 0oC. The SI unit of temperature is Kelvin.
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3. 4.
The temperature – 273oC is called absolute zero or zero Kelvin. At constant pressure, the volume of a fixed mass of a gas is directly proportional to its absolute temperature.
5.
The mathematical form of Charles’s law is V=KT.
6.
Charles’s law equation is
7.
At constant temperature, the volume of a given mass of dry gas is inversely proportional to it pressure is Boyle’s law.
8.
At constant temperature, the volume of a given mass of dry gas is inversely proportional to it pressure.
9.
The mathematical form of Boyle’s law is PV = K.
10.
Product of the volume and pressure of a given mass of dry gas is a constant.
11.
Boyle’s law equation is P 1 V 1 = P2 V 2 .
12.
The SI unit of pressure is pascal.
13.
The random movement of gaseous molecules from the region of higher concentration to a region of lower concentration is known as diffusion.
14. 15. 16.
Smell of hot food reaches faster because of faster rate of diffusion. Diffusion takes place only when the gases do not react with one another. Volume of gas diffusing per unit time is called rate of diffusion.
17.
The rate of diffusion of a gas is inversely proportional to the square root of its density is Graham’s law of diffusion.
18.
The rate of diffusion of a gas is inversely proportional to the square root of its density.
19.
The mathematical form of Graham’s law of diffusion is r =
V2 V2 . = T1 T2
K
.
d
v . m
20.
The relationship between diffusion and mass is r = K
21.
Rate of diffusion is inversely proportional to mass of the gas.
22.
Bhopal gas tragedy is due to methyl Isocyanate.
*****
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Chapter 19: Plant & Animal Breeding 1.
B19
What are food crop plants? Plants which are grown and cared in the fields, to serve as food or as a source of any food product and harvested seasonally are called food crop plants.
2.
How are crop plants classified? Give example for each. Crop plants are classified on the basis of the products obtained into cereals Crop type
Example Additionalexamples
1.
Cereals
2.
Pulses
Beans
Peas, dal
3.
Spices
Pepper
turmeric, garlic, cloves
4. 5.
Beverages Oil crops
Paddy (rice) Maize, Wheat, oats
Coffee tea, coco Ground nut coconut, olive, corn
6. Sugar crops Sugar cane beetroot 7. Fibre crops Cotton jute, flax, hemp 8. Plantation crops Coconut banana, rubber, cashew 9. Root crops Carrot raddish, onion 10. Tuber crops 3.
Potato
groundnut, yam
How are food crops classified? Food crops are classified into two types based on the season of cultivation or harvesting. They are a) Kharif crops 2) Rabi crops.
4.
What are Kharif crops? Give example. The crops that are raised in rainy season and harvested at the end of monsoon season (during September and October) are called Kharif crops. Ex: Rice, maize, pea, groundnut
5.
What are Rabi crops? Give example. The crops that are raised in winter season and harvested in the summer (during March & April) are called Rabi crops. Ex: Wheat, barley, mustard
6.
Differentiate between Kharif and Rabi crops. Kharif crop The crops that are raised in rainy season and harvested at the end of monsoon season (during September and October)
7.
Rabi crop The crops that are raised in winter season and harvested in the summer (during March & April)
What does conventional plant breeding involve? a) Developing new varieties of plants to suit varying climatic conditions. b) Improving taste or nutritional value c) Equip the plants to cope better with diseases and pests. d) Making the plants to use water and nutrients more efficiently.
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What is the aim of conventional plant breeding? The aim of conventional plant breeding is crossing of two closely related plants to combine the favourabletraits from both the plants and eliminate their unwanted traits.
9.
Define the term variety with respect to plant breeding. The term variety describes a group of plants similar in their gene composition but different in a few characteristics.
10.
What are the different procedures followed in conventional plant breeding? a) Selection
11.
b) Hybridization
c) Polyploidy
d) Induced mutation
What is meant by selection in conventional plant breeding? Selection is the process where a breeder selects from a population of plants having desirable characteristics. It is the most ancient and basic procedure.
12.
What is meant by hybridization? Hybridization is a technique of plant breeding that brings together desired traits through cross pollination.
13.
Mention the types of hybridization. The three types of hybridization are: a) Intervarietal hybridization b) Interspecific hybridization c) Intergeneric hybridization
14.
What is intervarietal hybridization? Intervarietal hybridization is a technique in which different varieties of the same species are mated to obtain a new variety. Ex: Different varieties wheat can be mated to obtain a new variety.
15.
What is interspecific hybridization? Interspecific hybridization is a technique in which crop species are mated with a related species. Ex: Sugarcane varieties are grown by interspecific hybridization.
16.
What is intergeneric hybridization? Intergeneric hybridization is a technique in which two members of two related genera are mated to get a totally new kind of plant. Ex: A specie of wheat, Triticum turgidum is created by cross breeding with a species of rye to get a new variety called Triticale.
17.
Differentiate between inter-specific hybridization and inter-generic hybridization. Inter-specific hybridization A technique in which crop species are mated with a related species.
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What is meant by polyploidy? The technique of developing polyploids is called polyploidy.
19.
What are polyploids? Plants with multiple sets of chromosomes are called polyploids.
20.
How are polyploids achieved? In a normal plant, 2 sets of chromosomes (diploid) are present. It is increased to 3n or 4n or 6n artificially by a chemical called colchicine.
21.
What is the advantage of polyploid plants? a) Polyploid plants are bigger in size. b) Polyploid plants show greater genetic variability.
22.
What is the disadvantage of polyploid plants? Polyploid plants less fertile and growth is very slow.
23.
Give reason: Polyploids have both advantages and limitations. Polyploid plants are bigger in size and show greater genetic variability but the plant fertility is lower and growth is very slow.
24.
What is induced mutation? The technique of growing crop plants by making genetic changes by using certain agents is called induced mutations.
25.
What are mutagens? The agents which bring about genetic changes in plants are called mutagens.
26.
What are mutants? The plants which are genetically changed by using chemical are called mutants.
27.
Differentiate between mutant and mutagens. The plants which are genetically changed by using chemical are called mutants and the agent which brings about changes in plants are called mutagens.
28.
Give reason: Induced mutation is not widely used. The method of induced mutations is not widely used since the site of mutation cannot be controlled.
29.
What is tissue culture? The technique of growing plant cells and tissues in a suitable culture medium, under controlled laboratory conditions is called tissue culture. OR Tissue culture is the practice of growing an entire plant from a single cell or tissue under aseptic, laboratory conditions.
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Define totipotency. Totipotency is the capacity of a cell to differentiate into a new organism.
31.
Mention the uses of tissue culture. a) Tissue culture is extensively used for large scale propagation of medicinal and ornamental plants. b) It is also used for propagating crop and forest plants. c) It is used for developing disease free plants. d) Cell culture is used for the extraction of many useful metabolites.
32.
What is genetic modification? The process in which a specific gene responsible for desired trait is selected and introduced directly into the new plant variety is called genetic modification.
33.
What are genetically modified plants or transgenic plants? The plants in which a specific gene responsible for desired trait is selected and introduced directly into the new plant variety are called genetically modified or transgenic plants.
34.
What are the merits and demerits of transgenic plants? Merits of transgenic plants: a) Crops are more productive and have a larger yield. b) Transgenic plants can offer more nutrition and flavour. c) A possibility that they could eliminate allergy causing properties in some foods. d) Crops can have resistance to pests, weeds and disease. e) Crops are more capable of surviving in regions with poor soil or adverse climates. f) Crops are more environment friendly as they require less herbicides and pesticides. g) Foods are more resistant and stay ripe for longer so they can be shipped long distances or kept on shop shelves for longer periods. h) Crops can be grown on small part of land. Demerits of transgenic plants: a) The use of genetically modified food should not be encouraged without research into the risks. b) Not labelling transgenic foods is wrong and unfair to the consumers who should have the right to know what they are buying so they can decide for themselves whether they want to buy the food or not. c) Genetically modified crops pose a risk to food diversity as the plants are much more dominant. d) Transgenic crops could give rise to super-weeds and super-pests that would need newer, stronger chemicals to destroy them. e) Transgenic crops cross-pollinate with nearby non-transgenic plants and could create ecological problems. f) The new technology interferes with traditional agricultural methods.
35.
What is recombinant DNA technology?
36.
Recombinant DNA technology is the technique of manipulation of genetic material of an organism under laboratory conditions. DNA containing the desired gene is isolated from a cell and then transferred into a new host cell with the help of carrier or Vector DNA. What is carrier DNA or vector DNA?
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B19: Plant & Animal breeding
The DNA which is used to transfer the desired gene isolated from another cell into a new host is called carrier DNA or vector DNA. Give examples of some genetically modified plants. No.
38.
201
Traits/products
Example
1
Herbicide resistant
Corm, potato, tomato, tobacco, cotton
2
Pest resistant
Corn, cotton, potato, tomato
3
Virus resistant
Papaya, cucumber, water melon, tomato, potato
4
Nitrogen fixation
Leguminous plants
5
Vitamin A enriched Golden rice
Write a note on BT Cotton. BT Cotton is a genetically modified or transgenic plant. It is a new variety in which a gene isolated from a bacterium called Bacillus thuringiensis has been newly introduced. The gene us responsible for producing a toxin which can kill the boll worm that attack the cotton plants.
39.
What is hydroponics? Hydroponics is the practice of growing plants in mineral nutrient solutions in water, without soil.
40.
What is the principle of hydroponics? Hydroponics is based in the principle that when the required mineral nutrients are directly introduced into the supply system of a plant artificially, soil is no longer required for a plant to survive.
41.
How are plants grown by hydroponics? In hydroponics, terrestrial plants are grown by immersing their roots in nutrient solution in specially designed containers.
42.
Mention the advantages of growing plants by hydroponics. a) Soil is not required. b) Water requirement is less. c) Yields are stable and high. d) There will no weeds to remove. e) Plants grow healthier.
43.
What is the disadvantage of growing plants by hydroponics? The main disadvantage growing plats by hydroponics is that it leads to rapid plant death.
44.
What is meant by aeroponics? The practice of growing plants where the roots of a plant are either continuously or discontinuously kept in an environment saturated with fine drops of mineral nutrients.
45.
How are plants grown by aeroponics?
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Plants are grown in a green chamber with excellent aeration. The roots hang in air. Nutrient solutions are sprayed frequently. 46.
Name the plants that can be grown by aeroponics. Potato, tomato and many leafy vegetables.
47.
Give reason: hydroponics and aeroponics methods are important for space research organisations Hydroponics and aeroponics methods are significant for space research organizations in developing special kind of food for astronauts. Mist is easier to handle in zero gravity situations than liquids in zero gravity situations.
48.
Differentiate between hydroponics and aeroponics. Hydroponics The practice of growing plants in mineral nutrient solutions in water, without soil.
49.
Aeroponics The practice of growing plants where the roots of a plant are either continuously or discontinuously kept in an environment saturated with fine drops of mineral nutrients
What is meant by roof-top gardening? The technique of growing plants on roof top in urban areas where sufficient space is not available is called roof-top gardening.
50.
What are the steps to be taken before starting roof-top garden? Precautions must be taken to prevent the leakage of water from roof due to seepage of water. Measures must be taken to enable the roof to bear the additional weight of plants. And soil.
51.
Give reason: Roof-top gardening may be a solution to various environmental problems. Explain What are the benefits of roof-top gardening? In urban areas where sufficient space is not available for growing plants, roof-top garden helps. a) Roof-top gardens increase access to safe outdoor green space. b) It improves air quality due to increased absorption of carbon dioxide. c) It provides habitat for butterflies and birds. d) It becomes a source of recreation. e) It encourages urban food production. f) It also provides a temperature control mechanism, by insulating the heat. g) Rooms under roof-top garden are 3 to 4 degree Celsius cooler than the surrounding temperature.
52.
Define animal husbandry. The various aspects related to feeding, breeding, caring and sheltering of animals in service of mankind is called animal husbandry.
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Define livestock. Live stock is a collective term used to describe animals domesticated by man for various uses. Cattle, pig, sheep, goat, fowl and duck are common examples of livestock.
54.
How is livestock classified? Give one example of each. On the basis of their utility, livestock is classified into: Utility
Examples
Milk yielding animals
Cow, goat, buffalo, camel
Meat & egg yielding animals
Fowl, duck, hen
Animals for agriculture & transport Bullocks, camel
55.
Wool & leather yielding animals
Sheep, camel
Honey, silk and lac yielding
Honey bee, silkworm, lac insect
What are the main objectives of animal breeding? a) Improving the growth rate. b) Increasing the production of milk, meat, egg, wool and other products. c) Improving the quality of products. d) Improving the resistance to diseases. e) Improving the span of productivity. f) Increasing the rate of reproduction.
56.
State the main approaches for animal breeding. The main approaches for animal breeding are in-breading, out-crossing and hybridization.
57.
What is meant by in-breeding? In-breeding is a method of animal breeding in which male and female individuals of the same species among the breeds.
58.
What is meant by out-crossing? Out-crossing is a method of animal breeding in which superior male of one breed is crossed with superior females of another breed.
59.
What is meant by hybridization? Hybridization is a method of animal breeding in which superior male of one species is mated with superior female of a different species.
60.
Mention the difference between in-breeding and out-crossing. In-breeding Crossing of male and female individuals of the same species.
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Genetic disorders are common in off springs Desirable qualities of two breeds appear in the off springs. 61.
Name some indigenous breeds of cow Sindhi, Sahiwal, Gir, Hallikar
62.
Name some exotic breeds of cow. Jersey, Holstein, Brown Swiss, Friesian
63.
Name some cross breeds of cows. Karan Swiss, Karan Fries, Frieswal, Karan
64.
What are transgenic animals? Animals in which a specific gene responsible for desired trait is selected and introduced directly into the new animal variety are called transgenic animals.
65.
Give some examples of transgenic animals. a) Introducing certain human gene sequences into cattle, goat and sheep for enhanced growth, meat and milk production. b) Bacterial genes introduced into sheep have resulted in improved wool output. c) Cattle containing human gene responsible for production of growth hormone, have shown production of milk containing human growth hormone.
66.
What are food additives? How are they classified? The substances which increase the shelf-life and nature of food are collectively known as food additives. Food additives are classified into a) Natural additives b) Man-made additives c) Artificial additives d) Antioxidants e) Colourants f) Flavourants g) Sweeteners
67.
Name some natural additives. Extracts from saffron, beetroot plant are used as colouring agents.
68.
Name a man-made additive. The additives which are synthetic copies of naturally occurring substances. Ex: Saccharine
69.
Name some artificial additives. The additives which are produced synthetically and not found in nature.
70.
What are preservatives? The substances which prevent the growth of microorganisms that cause spoilage of food are called preservatives. Ex: Common salt
71.
What are antioxidants? The substances which prevent food containing fat or oil from developing a foul smell are called antioxidants.
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What are colourants? The substances which restore colour lost during processing of food are called colourants.
73.
What are flavourants?
74.
The substances that are used to add a particular taste are called flavourants. What are sweeteners? Substances that are added to increase the intensity of sweetness are called sweeteners.
75.
Differentiate between antioxidant and colourant. Antioxidant The substances which prevent food containing fat or oil from developing a foul smell.
76.
Colourant The substances which restore colour lost during processing of food
Give reason: a) Food additives are widely used in modern life. Food additives are widely used to increase the shelf-life and nature of foods. b) Addition of artificial food additives should be minimized. Food additives if used regularly can cause health problems.
Fill in the blanks: 1. Plants which are grown and cared in the fields are called crops. 2.
The crops that are raised in rainy season and harvested at the end of monsoon season are called Kharif crops.
3. 4.
Rice is an example of kharif crop. The crops that are raised in winter season and harvested in the summer are called Rabi crops.
5.
Wheat is an example of Rabi crop.
6.
The process where a breeder selects from a population of plants having desirable characteristics is called Selection.
7.
Variety describes a group of plants similar in their gene composition but different in a few characteristics. Hybridization is a technique of plant breeding that brings together desired traits through cross pollination.
8. 9.
The technique in which crop species are mated with a related species is called interspecific hybridization.
10.
The technique in which different varieties of the same species are mated to obtain a new variety is called intervarietal hybridization.
11.
A technique in which two members of two related genera are mated to get a totally new kind of plant is called intergeneric hybridization.
12.
An example of a crop grown by intervarietal hybridization is wheat.
13.
An example of a crop grown by interspecific hybridization is sugarcane.
14. 15.
An example of a crop grown by intergeneric hybridization is triticale. Triticale is obtained from intergeneric hybridization of a species of rye.
16.
The number of chromosomes in a normal plant is 2n.
17.
The number of chromosomes in polyploids is 3n / 4n / 6n.
18.
The technique of developing polyploids is called polyploidy.
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19. 20.
Plants with multiple sets of chromosomes are called polyploids. A chemical used to induce polyploidy is colchicine.
21. 22.
The technique used to obtain genetically modified plants is called induced mutations. Genetic changes can be brought in a plant by using certain agents called mutagens.
23.
The plants which have been genetically changed are called mutants.
24.
The practice of growing an entire plant from a single cell or tissue in aseptic, laboratory conditions is called tissue culture.
25. 26.
The basis for tissue culture is totipotency of plant cells. The capacity of a cell to differentiate into a new organism is called totipotency.
27.
Transgenic plants are obtained by using recombinant DNA technology.
28.
Carrier gene used to transfer the desired gene into a new host cell is called vector DNA.
29.
The plants in which a specific gene responsible for desired trait is selected and introduced directly into the new plant variety are called genetically modified or transgenic plants.
30.
The practice of growing plants in mineral nutrient solutions in water, without soil is called hydroponics.
31.
In hydroponics, soil is not required.
32.
The disadvantage of hydroponics is rapid death of plant.
33.
The practice of growing plants where the roots of a plant are either continuously or discontinuously kept in an environment saturated with fine drops of mineral nutrients is called aeroponics.
34.
An example of a plant grown by aeroponics is potato/ tomato/leafy vegetables.
35.
Hydroponics and aeroponics are significant in the field of space science.
36.
The technique of growing plants on roof top in urban areas where sufficient space is not available is called roof-top gardening.
37.
Roof-top gardens improve air quality due to increased absorption of carbon dioxide.
38.
The various aspects related to feeding, breeding, caring and sheltering of animals in service of mankind is called animal husbandry.
39.
The collective term used to describe animals domesticated by man for various uses is livestock.
40.
An example of livestock is cattle, pig, sheep, goat, fowl and duck.
41.
The method of animal breeding in which male and female individuals of the same species are mated is called in-breeding.
42.
The method of animal breeding in which superior male of one breed is crossed with superior females of another breed is called out-crossing.
43.
An example of indigenous breed of cow is Sindhi/Sahiwal/Gir/Hallikar.
44.
An example of exotic breed of cow is Jersey/Holstein/Brown Swiss/Friesian.
45. 46.
An example of cross breed of cow is Karan Swiss/Karan Fries/Frieswal Karan. The substances which increase the shelf-life and nature of food are collectively known as food additives.
47.
Substances used to improve the nature of food with an increase in its shelf-life is called food additive.
48.
The method of animal breeding in which superior male of one species is mated with superior female of a different species is called hybridization.
49.
Animals in which a specific gene responsible for desired trait is selected and introduced directly into the new animal variety are called transgenic animals.
50.
The substances which increase the shelf-life and nature of food are collectively known as food additives.
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51. 52.
An example of a natural additive is saffron/beetroot. An example of a man made additive is Saccharine.
53.
The additives which are synthetic copies of naturally occurring substances are called man made additives.
54.
The additives which are produced synthetically and not found in nature are called artificial additives.
55.
The substances which prevent the growth of microorganisms are called preservatives.
56. 57.
Food additives used to prevent the spoilage of food are called pre The substances which prevent food containing fat or oil from developing a foul smell are called antioxidants.
58. 59.
The substances which restore colour lost during processing of food are called colourants. The substances that are used to add a particular taste are called flavourants.
60.
The substances that are added to increase the intensity of sweetness are called sweeteners.
61.
The substances which prevent the growth of microorganisms that cause the spoilage of food are called preservatives.
62.
The substances which increase the shelf life of food is called preservative.
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B20
1. What is irritability? Irritability is the unique property of all living organisms to respond to changes in the environment. 2.
Give an example of irritability. If an earthworm is touched, it moves away from the place. Plants grow towards the light.
3.
What are plant hormones? The special chemicals which bring about coordination in plants are called plant hormones.
4.
What is meant by tropism? The movement of plants in response to various stimuli is called tropism.
5.
Define the following. a) Phototropism – The response of plants towards light b) Geotropism – The response of plants towards gravity c) Hydrotropism – The response of plants towards water d) Thigmotropism – The response of plants towards touch e) Thermotropism – The response of plants towards temperature/heat f) Chemotropism – The response of plants towards chemicals
6.
Give reason: Response in plants cannot be observed immediately Response in plants is very slow. Hence it cannot be observed immediately.
7.
Give examples show that not all responses in plants are slow. Insectivorous plants like Venus fly trap responds very quickly to touch. The leaflets of touch me not plant (Mimosa Pudica) get folded immediately on touching.
8.
What are phytohormones? Give example. Plant hormones are also called phytohormones. They are organic compounds which are produced by tissues that regulate plant growth and development.
9.
Give reason: Phytohormones are also called growth regulators. Phytohormones are organic compounds which regulate plant growth and development in plants. Hence they are called growth regulators also.
10.
Mention the types of growth regulators and give example. a) Plant growth promoters ex: Auxins, Gibberellins, cytokinins b) Plant growth inhibitors ex: Abscisic acid, Ethylene
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Mention the functions of plant growth regulators. Plant growth regulators promote cell division, cell enlargement/elongation and cell differentiation. They induce photropic movement of shoot system.
12.
Mention the two methods of co-ordination of organ system in multi-cellular organisms. Co-ordination of various organ systems in multi-cellular organisms is brought about in two ways a) Control by nervous system b) Control by endocrine system
13.
Mention the two ways of transferring information from one part of the body to another. a) Sending chemical signals through the blood b) Sending electrical signals through the nerves.
14.
What is a gland? Which are the two types of glands in our body? A gland is an organ made up of cells which are specialised for secretion of particular chemical substances. The two types of glands are glands with ducts (exocrine glands) and glands without ducts (endocrine glands).
15.
What are exocrine glands? Give example. The glands that discharge their secretions through the ducts to their target organs are called exocrine glands. Ex: Salivary gland, pancreas.
16.
What are endocrine glands? Give example. The glands that discharge their secretions directly into blood stream are called endocrine glands. Example: Pituitary gland, Thyroid gland
17.
Differentiate between exocrine and endocrine glands. Exocrine glands
18.
Endocrine glands
They have ducts
They do not have ducts
The secretions pass through ducts to target organs
The secretions pour directly into the blood
They secrete enzymes
They secrete hormones
What are hormones? The chemical substances secreted by endocrine glands for the control and co-ordination of various activities of the body are called hormones.
19.
What are target organs?
20.
The organs on which the hormones act, control or co-ordinate are called target organs. Why are hormones called chemical messengers? Hormones are chemical substances that carry stimuli from one part of the body to another.
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Name the major endocrine glands. a) Pituitary gland b) Thyroid gland c) Parathyroid gland d) Adrenal gland e) Islets of Langerhans f) Gonads
22.
Where is pituitary gland located? Write its functions. Pituitary gland is a tiny gland situated at the base of the brain. The functions of pituitary gland are: 1) It influences the rate of both physical and mental growth of the body. 2) It controls and regulates the production of hormones in other glands. a) stimulates the secretion of hormones from thyroid gland. b) regulates the secretion of hormones from adrenal gland. c) controls the synthesis of melanin in the skin c) stimulates secretion of milk from mammary gland. d) excretion of water from the kidneys. e) contraction of muscles of uterus. f) It stimulates the production of gametes from gonads (ovary and testis) g) It stimulates the secretion of sex hormones by the gonads.
23.
Mention the hormones secreted by pituitary gland and state their function. Name of hormone
Short form
Function
Growth hormone or (Somato Trophic Hormone)
STH
Regulates both physical and mental growth
Thyroid Stimulating Hormone
TSH
Stimulates the secretion of hormone from thyroid gland
Adreno Cortico Tropic Hormone
ACTH
Regulates the secretion of hormones from adrenal gland
Melanocyte Stimulating Hormone
MSH
Controls the synthesis of melanin in skin
Prolaction
-
Stimulates the secretion of milk from mammary glands
Vasopressin
-
Controls the excretion of water from kidneys Stimulates the constriction of uterus muscles during child birth.
Oxytocin
-
Follicle Stimulation Hormone
FSH
Stimulates the production of gametes from gonads
Leutinising Hormone
LH
Stimulates the secretion of sex hormones by the gonads
Stimulates the ejection of milk from mammary gland
24.
Which hormone is called growth hormone?
25.
Somato Trophic Hormone is called growth hormone. Why is pituitary hormone referred to as ‘growth hormone’?
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Somato Trophic Hormone which is secreted by pituitary gland regulates both physical and mental growth. Hence it is called as growth hormone. Why is oxytocin call ‘Birth hormone’? Oxytocin stimulates the constriction of uterus muscles during child birth and ejection of milk form mammary glands. Hence it is referred to as Birth hormone.
27.
Why is pituitary gland called ‘The conductor of endocrine orchestra’? Pituitary gland secretes many hormones which control the functioning of other endocrine glands like thyroid gland, adrenal gland, gonads etc. Hence pituitary gland is called the conductor of endocrine orchestra.
28.
What is gigantism? Gigantism is a condition of the body in which the growth rate is very high due to the over secretion of growth hormone prior to puberty.
29.
What is dwarfism? Dwarfism is a condition of the body in which there is retarded growth due to the under secretion of growth hormone prior to puberty.
30.
What is acromegaly? What are its symptoms? The disease caused in adults due to over secretion of growth hormone is called acromegaly. The symptoms are disproportionate growth of bones particularly jaws, nose, hands and legs.
31.
What is Diabetes incipidus? Diabetes incipidus is a disease caused due to the low secretion of Anti Diuretic Hormone (ADH) in the body. In this disease, the person passes large quantity of dilute urine
32.
Give reason: Person suffering from diabetes incipidus pass large quantity of dilute urine. Since reabsorption of water in the kidneys has decreased
33.
Where is thyroid gland located? Name the hormone secreted. Thyroid gland is located close to the throat region, below the pharynx in front of the trachea. Thyroid gland secretes a hormone called thyroxin.
34.
Write the composition of thyroxin. Thyroxin is composed of amino acid and iodine.
35.
Mention the functions of thyroxin. a) Thyroxin influences the rate of metabolism. b) It increases the production of heat in the body. c) It promotes mental and physical development of the body.
36.
Why is thyroxin referred to as ‘Personality hormone’?
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Thyroxin indirectly affects the growth and development of body. Hence it is called personality hormone. 37.
What is hypothyroidism? Mention the abnormalities caused due to it. Hypothyroidism is a condition in which the thyroid gland fails to produce enough thyroxin to meet the normal requirements of the body. Hypothyroidism leads to simple goitre, myxoedema and cretinism.
38.
What is simple goitre? What are its symptoms? The disease caused due to deficiency of iodine in the food is called goitre. The symptoms of goitre are abnormal enlargement of thyroid gland in the neck region.
39.
How can goitre be prevented or cured? Goitre can be prevented by providing sufficient iodine along with food and water. Using iodized salt while cooking food can prevent goitre.
40.
Why do people living in coastal regions do not suffer from goitre? People living in coastal regions do not suffer from goitre as they use sea water and sea food which are rich in iodine.
41.
Why is goitre called ‘endemic disease’? Goitre is a localised disease and found in areas where iodine is less in soil and water. Hence goitre is referred to as endemic disease.
42.
What is cretinism? What are its symptoms? Cretinism is a disorder caused in children due to improper functioning of thyroid gland. The symptoms are stunted growth, retarded mental development, bow legs, defective teeth, protrusion of tongue and loose wrinkled skin.
43.
A child is mentally retarded with defective teeth and loose wrinkled skin. a) From which disease is the child suffering? b) What is the disease due to? The child is suffering from cretinism. The disease is caused in children due to improper functioning of thyroid gland.
44.
What is myxoedema? What are its symptoms? Myxodedma is a disorder caused due to under secretion of thyroxin in adults. The symptoms are low metabolic rate, loss of mental and physical vigour, thickening of skin, low rate of heart beat.
45.
46.
What is hyperthyroidism? What are its symptoms? The disorder caused due to over secretion of thyroxin is called hyperthyroidism. The symptoms are high metabolic rate, protrusion of eye balls, high blood pressure, nervous tension, irritability, profuse sweating, weight loss and fatigue. Where are parathyroid glands located? Mention the hormone secreted. Mention the disorder caused due to its under secretion and over secretion. State its function. Parathyroid glands are embedded in the tissues of thyroid gland.
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Parathyroid gland secreted a hormone called parathormone. The function of parathormone is to control the amount of calcium salts in blood and bones.
47.
Under secretion of parathormone leads to painful muscle cramps. Over secretion of parathormone removes calcium from the bones making them soft and spongy. Why is pancreas considered as ‘mixed heterocrine gland’? Pancreas is a mixed heterocrine gland because a portion of pancreas functions as an exocrine gland and another portion functions as endocrine gland.
48.
What are islets of Langerhans? The cells of endocrine gland of pancreas are called islets of Langerhans.
49.
Mention the hormones secreted by islets of Langerhans. State their function. The hormones secreted by islets of Langerhans are insulin and glucagon. The functions are: Insulin promotes the conversion of glucose to glycogen for storage in liver and muscles. It is secreted when blood glucose levels are high. Glucagon influences the conversion of glycogen into glucose. It is secreted when blood glucose levels are low.
50.
What is the role of insulin in regulating the level of glucose in the blood? Insulin promotes the conversion of glucose to glycogen for storage in liver and muscles. It is secreted when blood glucose levels are high.
51.
What is diabetes mellitus? What are its symptoms? How can it be controlled? Diabetes mellitus is a disorder or condition caused when sufficient insulin is not produced and the glucose level in blood increases which is excreted through urine. The symptoms of diabetes are frequent urination and thirst. Diabetes mellitus can be controlled by administering insulin injection of suitable doses.
52.
Differentiate between diabetes mellitus and diabetes insipidus. Diabetes Mellitus
53.
Diabetes Insipidus
It is caused by hypo secretion of insulin in the body
It is caused by hypo secretion of Anti Diuretic Hormone (ADH) in the body
The patient passes glucose through urine.
The patient passes large amounts of dilute urine.
Blood glucose level is high
No increase in blood glucose levels
Where are the adrenal glands located? Mention the parts of the adrenal gland. The adrenal glands are located on the upper part of each kidney. Each adrenal gland has two parts an outer cortex and inner medulla.
54.
Name the hormone secreted by the adrenal cortex. Mention its function.
55.
One of the important hormones secreted by adrenal cortex is cortisone. It regulates the rate of metabolism and the concentration of salts in the blood. Mention the hormones secreted by adrenal medulla. Adrenal medulla secretes three hormones adrenaline, nor-adrenaline and dopamine.
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56.
Mention the functions of adrenaline.
57.
a) Adrenaline prepares the body to face emergency by producing adrenaline in excess during fear, anger, anxiety or emotional stress. b) It brings about co-ordination in heart beat, respiration and dilation of pupils. Why is adrenaline referred to as ‘emergency hormone’? Adrenaline prepares the body to face emergency and brings co-ordination of several events like increased heart beat, rate of respiration, dilation of pupil and other parts of the body. Hence adrenaline is referred to as emergency hormone.
58.
Why is adrenaline also called fright, fight and flight hormone? Adrenaline is secreted in excess and prepares the body to face the emergency situations. It helps us to overcome fright (fear), fight or run away (flight). Hence it is called fright, fight or flight hormone.
59.
Assume that you are attacked by robbers as you walk alone. At the moment you start running at a great speed. Which hormone produced in the body is responsible for getting that speed? Adrenaline
60.
What are gonads? Gonads are the sex glands. Gonads produce sex hormones after the attainment of puberty.
61.
Name the hormones produced by gonads. a) Testis secretes the male sex hormone androgen. b) Ovaries secretes the female sex hormone estrogen
62.
Name the hormone secreted by testis. State its function. Testis secretes the male sex hormone called androgen. The most common hormone is testosterone. The function of testosterone is to help in the appearance of masculine characteristics at puberty.
63.
Name the hormone secreted by ovaries. State its function. The ovaries secrete female sex hormones called estrogens. The function of estrogen is to help in the appearance of feminine characteristics at puberty.
64.
State the function of progesterone. Progesterone stimulates the changes in the uterus during menstrual cycle and pregnancy.
65.
Differentiate between Androgens and Estrogens. Androgens The male hormones produced by testis
66.
Estrogens The female hormones produced by overies
What is the importance of nervous system?
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a) Nervous system controls and coordinates various activities and functions of different organs and organ systems in the body. b) It regulates both voluntary and involuntary activities of the body. c) It enables us to adjust to the environment or situation. d) It enables us to think, reason and remember. 67.
e) It controls all the reflex actions of the body. What is a neuron? A neuron or nerve cell is a special type of cell that is the basic, structural and functional unit of nervous system.
68.
Name the three divisions of the nervous system. Nervous system consists of receptors, effectors and conductors.
69.
What are these? a) Receptor: the organ that receives the stimulus is called receptor. Ex: Sense organs b) Effector: the organ that shows visible response is called effector. Ex: muscles & glands c) Conductors: The tissues that transmit nerve impulses from all the parts of the body to nerve centres are called conductors. Ex: nerves
70.
Name the three divisions of the human nervous system. The human nervous system consists of three components namely a) Central Nervous System (CNS) b) Peripheral Nervous System (PNS) c) Autonomic Nervous System (ANS)
71.
Briefly explain the Central Nervous System. a) The components of the central nervous system are brain and spinal cord. b) The brain and the spinal cord are covered by three membranes namely outer Duramater, middle Arachnoid and the inner piamater called meninges. The space between the meninges is filled by the cerebro-spinal fluid. This fluid circulates between the brain and the spinal cord.
72.
What are meninges? Meninges are the layers of connective tissue that surrounds the brain and spinal cord.
73.
How is the brain protected? a) Meninges act as a cushion against bumps and jolts. b) Cerebro-spinal fluid protects from injuries. c) Brain is also protected by a bony case called cranium.
74.
What is the advantage of Cerebro Spinal Fluid (CSF) to brain and spinal cord? a) CSF protects the brain and spinal cord from injuries b) It supplies nutrients to the nervous system.
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Name the parts of the human brain. Brain is divided into three parts – Fore brain, Mid brain & Hind brain.
76.
Name the major parts of the fore brain. The two major parts of the fore brain are cerebrum and Diencephalon.
77.
Briefly explain the cerebrum. a) Cerebrum is the largest part of the brain. b) It consists of two equal halves called cerebral hemispheres separated by a groove. c) The cerebral hemispheres are internally connected by a sheath of nerve fibres called Corpus callasum. d) Each hemisphere has two regions – an outer cortex and an inner medulla. e) The outer portion (cortex) contains cytons (cell body of neurons) which forms the grey matter. The grey matter is folded into ridges to form convolutions. f) The inner portion (medulla) of the cerebrum consists of white matter which contains axons of the neurons.
78.
What are convolutions?
79.
The surface of cerebrum has a number of folds and ridges called convolutions. What makes the cerebrum to have larger surface area? The surface of cerebrum has a number of folds and ridges which allows the cerebrum to have a larger surface area.
80.
Write the functions of cerebrum. a) Cerebrum is the seat of consciousness. b) Cerebrum has centres for intelligence, imagination, reasoning, emotions and will power.
81.
82.
Why is cerebrum called seat of consciousness? Cerebrum has centres for intelligence, imagination, reasoning, emotions, will power etc. which takes place when a person is consciousness. Hence it is called as the seat of consciousness. “An injury to the left cerebral hemisphere may result in paralysis of organs on the right side”. Give reason. The nerves coming from the right side of the body are connected to the left cerebral hemisphere.
83.
What is diencephalon?
84.
The parts of the brain that is below the cerebrum are together called diencephalon. Name the two parts of the diencephalon.
85.
The two major parts of the diencephalon are a) the upper thalamus b) the lower hypothalamus. State the function of thalamus. The function of thalamus is to receive nerve impulse from the sense organs and send them to the upper region.
86.
State the function of hypothalamus.
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a) Hypothalamus regulates body temperature, water balance, appetite and sleep. b) It controls autonomic nervous system. 87.
c) It forms a part of the pituitary gland. Write a note on mid brain. a) Mid brain is a small region of the brain made up of nerve fibres connecting cerebrum and cerebellum. b) It serves as a relay station for nerve impulses from hind brain to fore brain.
88.
Name the parts of the Hind brain. The three main parts of the hind brain are:
89.
a) Pons Varoli b) Cerebellum c) Medulla Oblongata What is cerebellum? Write its function. Cerebellum is a small region located between pons and medulla oblongata. The functions of cerebellum are: a) It is responsible for the maintenance of equilibrium and posture of the body. b) It co-ordinates and controls the movement of muscles in actions like walking or running.
90.
Give reason: A drunkard walks unsteadily.
91.
The alcohol affects the cerebellum which is responsible for maintaining balance of the body. It is not able to control and coordinate the movement of muscles while walking. What are pons? Write their function. Pons form the middle part of the hind brain. It acts as a conducting medium carrying impulse from one hemisphere of cerebellum to the other. Out of the 12 pairs of cranial nerves that arise from the brain, 4 pairs originate from the pons. The functions of pons are:
92.
a) It has controlling centres of mastication (chewing), facial expressions, and respiration. b) It forms the conducting pathway. What is medulla oblongata? State its function. Medulla oblongata is the region that is located at the base of the brain. It continues as the spinal cord. The functions of medulla oblongata are: a) It has centres that control the involuntary activities such as breathing, heart beat, movement of digestive tract (swallowing, coughing, vomiting), b) It is also involved in the secretion of enzymes c) It maintains blood pressure. Part of Brain
Function • Centre of consciousness, thought, imagination, memory, analytical thinking.
Cerebrum
• Awareness of vision, hearing, smell, taste, touch, heat etc. • Control of voluntary actions.
Cerebellum
Medulla oblongata Thalamus
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• Maintains balance and equilibrium of body. • Coordinates muscular activities. • Controls heart beat, breathing, contraction of blood vessels, gastrointestinal movements, vomiting, sneezing, coughing and other involuntary activities. • Relays transmission of impulses to the cerebrum and
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from the cerebrum. • Regulates the body temperature, water level etc. Hypothalamus
Pons
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• Centre of thirst, hunger, sexual drive etc. • Controls the secretion of pituitary hormones. • Controls mastication, facial expression, respiration. It forms a conducting pathway.
Describe the structure of the spinal cord. a) Spinal cord is a part of the central nervous system. b) It is a downward continuation of the medulla oblongata. c) It is a long cylindrical structure protected by the vertebral column. d) It is composed of large number of nerve cells and nerve fibres. e) It has grey matter in the centre surrounded by white matter. f) 31 pairs of nerves arise from the spinal cord and their branches reach several parts like heart, lungs, stomach etc,. g) The spinal nerves are made up of both sensory and motor nerve fibres.
94.
State the function of spinal cord. Spinal cord co-ordinates the movements of limbs and organs in the body by reflex action.
95.
What is reflex action? Which is the centre of such action? Reflex action is an automatic response to an external stimulus. The centre of reflex action is spinal cord. The actions are independent of the brain. Ex: a) when we touch a hot object, we withdraw out hand b) When we step on a thorn unknowingly we withdraw our leg.
96.
What is reflex arc? The pathway of the nerve impulse involved in reflex action is called reflex-arc.
97.
Mention the parts of a reflex arc. The five distinct parts of a reflex arc are: a) A receptor to receive stimulus (sense organs) b) Sensory neurons to conduct the impulses from receptors to the spinal cord or the hind brain. c) An association neuron to transmit the impulse from sensory neuron to a motor neuron. d) A motor neuron to pass the impulse to an effector. e) An effector to take necessary action in response to the stimulus.
98.
Show the pathway of a typical reflex action. Stimulus receptor sensory neuron Association neuron motor neuron effector.
99.
Distinguish between sensory nerves and motor nerves. Sensory nerves
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1. It carries impulses from sense organs to the brain
1. It carries messages from the brain to the muscles
2. It originates from the dorsal horn of the spinal cord
2. It originates from ventral horn of spinal cord
100. What is peripheral nervous system? Peripheral nervous system consists of the nerves between the brain, spinal cord and various organs. It includes 12 pairs of cranial nerves and 31 pairs of spinal nerves. 101. What are cranial nerves? Cranial nerves are the nerves that originate from the different parts of the brain. It connects the sense organs, muscles and glands of the head. 102. What is autonomic nervous system? Autonomic nervous system consists of a set of peripheral nerves that connect the organs like heart, lungs and digestive tract and other internal organs. 103. State the function of autonomic nervous system. The function of autonomic nervous system is to regulate the involuntary actions of the body. 104. Mention the two parts of the autonomic nervous system. The two parts of the autonomic nervous system are: a) Sympathetic system
b) para sympathetic system
105. Give an example to show that sympathetic and para-sympathetic system work opposite in function. Sympathetic system stimulates the pupil in the eye to dilate (open) where as parasympathetic system stimulates it to constrict (close). 106. What are sense organs? Name them. The organs through which we sense the objects in our environment are known as sense organs. The five sense organs are eyes, ears, nose, tongue and skin. 107. How are the eyes protected? OR Name the accessory parts of the human eye. State their function. The four accessory parts of human eye are eye brows, eye lid, eye lashes and lacrymal glands. a) The eye brows protect the eye from small particles that fall from above the eye and provide shade to the eyes from bright illumination. b) The eye lids regularly spread the tears and other secretions on the eye surface to keep it moist c) The eye lashes prevent dust particles from the entering eyes. d) The lacrymal gland produces tears which keep the surface of the eyes moist and wash the dust particles.
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108. What are lacrymal glands or tear glands? Lacrymal glands are the glands present in the outer region of the upper eye lid. It produces secretions that keeps the surface of the eyes moist and wash out dust when we blink. 109. Describe the structure of eye. a) The wall of the eye is made up of three layers namely outer sclera, the middle choroid and the inner retina. b) The sclerotic layer has a bulged, transparent portion called cornea. Cornea is protected by a thin membrane called conjunctiva. c) The choroid has an opening in the front in the centre called pupil. The pupil has tiny muscles arranged radially called iris. d) A transparent bi-convex lens is located behind the iris. The lens is held in position by ciliary muscles and suspensory ligaments. e) The area between the cornea and the lens is filled with a fluid called aqueous humour. f) The space between the cornea and the lens is filled with a thick fluid called vitreous humour. g) The inner retina layer contains receptor cells called rods and cones. 110. Give reason: Choroid is thick and rich with blood vessels Choroid has a layer of blood vessels which nourishes the back of the eye. 111. Which are the two fluids present in the eyeball? Mention their functions. The area between the cornea and the lens is filled with a fluid called aqueous humour. The space between the cornea and the lens is filled with a thick fluid called vitreous humour. The fluids help in refraction of light rays and maintain the shape of the eye ball. 112. What are these? a)
Sclera: It is the outermost layer of the eye
b)
Cornea: The bulged transparent front portion of the sclera. It allows light to enter the eyeball.
c)
Conjunctiva: It is a thin membrane that protects the cornea.
d)
Pupil: The tiny hole in the middle of choroid.
e)
Iris: It is a circular contractile diaphragm in front of the crystalline lens. Its function is to control the amount of light entering the eye. It is also responsible for the colour of the eye.
f)
Ciliary muscles: It is a muscle along with suspensory ligament holds the crystalline lens in position. It helps to alter the thickness of the lens, so that the image is clearly focussed on the retina.
g)
Aqueous humour: The fluid that is filled in the area between the cornea and the lens. It helps to maintain the shape of the eye ball & to keep the cornea moist.
h)
Vitreous humour: It is a thick fluid filling the space behind the lens. It helps to maintain the shape of the eyeball. It also helps in focussing the image clearly on the retina.
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i)
Rods: The receptor cells that are sensitive to dim light. They cannot distinguish colours.
j)
Cones: The receptor cells that are sensitive to bright light. They can distinguish colours.
k)
Yellow spot (Fovea): The depressed region located opposite to the pupil containing a large number of cones where a clear sharp image is formed.
l)
Optic nerve: The bundle of sensory nerve fibres emerging from the eye ball.
m) Blind spot: The region on the retina where the optic nerve exits the eye ball where no image is formed. Rods and cones are absent in this region.
113. Differentiate between yellow spot and blind spot Yellow spot
Blind spot
It is a region opposite to the eye lens
It is a region where the optic nerve exits the optic nerve
It is a region where a clear sharp image is formed
It is a region where no image is formed
It has a large number of rods and cones
It has no sensory cells.
114. Differentiate between rods and cones Rods
Cones
Rods are sensitive to dim light
Cones are sensitive to bright light
Rods cannot distinguish colours
Cones can distinguish colours
115. Explain the functioning of the eye. a) The light ray reflected from the object are focussed on the retina to from the image on the retina b) The receptor cells in the region are stimulated by photochemical reactions. c) The receptor cells convert the stimulations into electrical impulses. The impulses pass through the optic nerve to the visual centre in the cerebrum. d) The impulses are interpreted in the cerebrum, resulting in vision. 116. How is the human eye able to adjust to near and far objects? The human eye is able to adjust to near and far objects by altering the focal length of the lens. When we see a near by object, the muscles around the lens contract which increase the convexity of the lens. When we see a distant object, the muscles around the lens relax which decreases the convexity of the lens. 117. What is meant by accommodation of the eye? The ability of the eye lens to see both near by and far away objects clearly is called accommodation of the eye.
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118. Give reason: a) When we suddenly enter a cinema hall, we will not be able to see any objects. Our eyes take some time to adjust to the light in the surroundings. When we are in bright area pupil constricts. It remains same when we enter a cinema hall and takes time to dilate. Hence it takes some time to see objects. b) There is no image formation at blind spot. Blind spot is a region where the optic nerve exits the eye ball. There are no sensory cells. Hence no image is formed. 119. Mention the common defects of the eye. a) Myopic or short sight c) Presbyopia
b) Hyper-metropia or long sight d) Nyctolopia or night blindness
e) Cataract 120. What is myopia? How can it be corrected? Myopia is a defect of the eye in which the person can see near by objects but cannot see far off objects clearly. It is caused due to the bulging of the eye ball or elongation of the eye ball. It can be corrected by using concave lens. 121. Give reason: A concave lens is used to correct myopia. In a myopic eye light falls too short from the retina. A concave lens forces light to fall on the retina. Hence concave lens is used to correct myopia. 122. What is hyper-metropia? How can it be corrected? Hyper-metropia is a defect in which a person can see far off objects clearly but cannot see the near-by objects clearly. It is caused due to the flattening of eye ball. It can be corrected by using convex lens. 123. Give reason: A convex lens is used to correct hypermetropia. In a hypermetropic eye, light is focused behind the retina. A convex lens will force it to form on the retina. Hence a convex lens is used to correct hypermetropia. 124. What is Presbyopia? Presbyopia is a defect in which a person can see neither near-by nor far off objects clearly. It occurs at old age due to the loss of elasticity of eye lens. 125. What is cataract? Cataract is a disorder of the eye in which the lens of the eye becomes cloudy, causing partial or total blindness. 126. What is diabetic retinopathy? How can it be prevented? Diabetic retinopathy is a disorder of the eye that occurs in people suffering from diabetes. After many years of diabetes, the blood vessels of the retina may leak, close-up or begin to grow. This causes blood to enter the vitreous humour making it opaque. It can be prevented by early treatment with laser beam.
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127. What is vitrectomy? Vitrectomy is a major surgical procedure to treat diabetic retinopathy. In this procedure the blood that has leaked into the vitreous humour is removed and vision is restored. 128. A person is advised vitrectomy surgery. Which gland which is not functioning properly? Islets of Langerhans. 129. Due to what reason blood from retina would seep into vitreous hormone? What is the treatment for this condition? 130. What is astigmatism? How can it be corrected? Astigmatism is a defect in which, a person looking at horizontal or vertical lines appears distorted. It is caused due to the unevenness of the crystalline lens. It can be corrected by using cylindrical lenses. 131. What is Glaucoma? Glaucoma is a disorder of the eye. The eyeball of a person suffering from glaucoma gradually hardens. The person sees flashes of light and coloured rings around the objects. The vision gradually decreases and leads to blindness. It occurs in persons above forty years of age. 132. A person is not able to identify the colours in the traffic signal. What disease is he suffering from? The disease is called colour blindness. It is a genetic disorder in which a person is unable to differentiate colours. 133. What are the precautions to be taken regarding the care of the eyes? a) Do not strain your eyes by reading in dim light b) Avoid reading books during journey on roads. c) Avoid very bright light. d) Avoid watching television from a short distance. e) Avoid working on computers for a long time. f) Wash the eyes with cold clean water atleast twice a day. g) Consult an eye specialist in case of any problem. 134. Describe the structure of the human ear. a) The human ear is divided into three parts namely the outer ear, the middle ear and the inner ear. b) The outer ear consists of pinna, auditory canal and the tympanum. c) Pinna is a cartilageneous organ covered with skin. d) Tympanum is an obliquely placed membrane which separates the external ear from the middle ear. e) The middle ear consists of three bones namely malleus, incus and stapes. f) The middle ear is connected to the throat by an air passage called Eustachian tube. g) The inner ear has two parts namely utriculus and sacculus. The upper part or utriculus is connected to semi-circular canals. The lower part or sacculus is connected to cochlea.
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h) Cochlea has delicate structures called organ of corti, which have receptors that join to form the auditory nerve. 135. a) What is organ of corti? b) Name the liquids that are present in inner ear. a) Cochlea has delicate structures called organ of corti, which have receptors that join to form the auditory nerve. b) The entire ear is filled with a fluid called endolymph. The inner ear is surrounded by a fluid called perilymph. 136. Differentiate between endolymph and perilymph Endolymph It is the fluid which fills the inner ear
Perilymph It is the fluid that fills the entire ear
137. How is the ear protected? a) The auditory canal has hairs at its opening to prevent tiny particles from entering the ear. b) The wax secreting cells on the inner lining of the auditory canal produces wax that traps small organisms and dust. 138. What are these? State their function (if any) a) Pinna: It is a cartilagenous organ covered with skin. It collects sound waves and directs them into the auditory canal. b) Tympanum: It is an obliquely placed membrane at the end of the auditory canal. It helps in passing the sound waves from outside to the middle ear. c) Eustachian Tube: The air passage that connects the middle ear and the throat is called Eustachian tube. It equalizes the air pressure on either side of the ear drum. d) Utriculus: It is the upper part of the inner ear. It is connected to three semi-circular canals. It is concerned with the balance of the body. e) Sacculus: It is the lower part of the inner ear. It contains appendages called Cochlea. It also contains a delicate structure called organ of corti which forms the auditory nerve. 139. What are the cares to be taken of the ear? a) Hardened wax from the auditory canal should not be removed using sharp objects as they damage the eardrum. b) Loud noise must be avoided as they damage the eardrum. c) Visit a doctor if there is ear ache due to infection. d) Use hearing aid if there is a problem in hearing. e) Small insects entering the ear can be removed by filling the external ear with salt water. 140. Give reason: a) A strong blow on the ears is very dangerous.
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As it would damage the semicircular canals and cochlea. This would lead to leakage of of fluids and sometimes even death, with ear bleeding. b) When there is severe throat infection we normally get ear pain. Throat infections affect the middle ear because eustachian tubes connect the middle ears and the throat. 141. Briefly explain the structure of the human nose. The nasal cavity is lined by olfactory epithelium. The upper part of the nasal cavity has receptors of smell. The receptors are connected with the olfactory nerve. The olfactory nerve carries the impulses to the brain. 142. Briefly explain the sensation of smell. The molecules from the substance escapes and are carried by the inhaled air. On reaching the olfactory epithelium, they get dissolved in the mucus and stimulate the receptors. The stimulations are passed through the olfactory nerve to the brain. Here it interprets the impulses and gives the sensation of smell. 143. Why does food appear relatively tasteless when one has cold or running nose? When you put food in your mouth, odour molecules from that food travel through the enter nose and stimulate the olfactory receptor cells at the top of your nasal cavity, If mucus in your nasal passages becomes too thick, air and odor molecules cannot reach the olfactory receptor cells. Thus, the brain receives no signal identifying the odour Hence food eaten appears tasteless. 144. Explain how a pea or a button which has got into the nasal cavity be removed. OR What is the first aid to be provided to a person who got a pea or a button into the nasal cavity accidentally? If a pea or a button gets into the nasal cavity accidentally, give a pinch of snuff to the person. It causes violent sneezing and the foreign body will be thrown out. Visit a doctor if the above method does not work. 145. Explain the structure of tongue. The tongue is covered by a mucus membrane. It has numerous tiny sensory cells called taste buds. Taste buds are composed of a cluster of cells with receptors lying in a small depression on the surface. 146. Briefly explain the mechanism of taste. Food that is eaten mixes with saliva and enters the pores of the taste buds. They chemically stimulate the sensory cells. These cells convert the chemical stimuli into electrical impulses. The electric impulses pass to the brain through the sensory neuron. The brain interprets the impulses as taste. 147. Mention the location of the following taste.
Types of taste
Location (region of the tongue)
Sweetness
Front
Salt
Anterior margin
Sour
Sides
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Posterior
148. After relay race, Runner-A pours glucose powder into his mouth. Runner-B tastes the glucose slowly with the tip of his tongue. Whom do you think, experiences the sweetness most? Why? Runner-B experiences most sweetness because the taste buds of sweetness are distributed in the front. 149. What structures enable the skin to function as a sense organ? Sensory receptors are distributed all over the skin which perceive the stimuli. Touch receptors are located near the surface of the skin. Pressure receptors and pain receptors are located deep inside the skin.
150. Draw a neat labelled diagram of the vertical section of the human eye.
151. Draw a neat diagram of the structure of human ear and label the parts.
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Fill in the blanks: 1. In plants coordination is brought about by special chemicals called plant hormones. 2. The movement of plants in response to various stimuli is called tropism. 3. The response of plants towards light is called phototropism. 4. The response of plants towards gravity is called geotropism. 5. The response of plants towards water is called hydrotropism. 6. The response of plants towards touch is called Thigmotropism. 7. The response of plants towards temperature/heat is called Thermotropism. 8. The response of plants towards chemicals is called chemotropism. *****
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Chapter 21: Heredity 1.
B21
Define genetics. Genetics is a branch of biology which deals with a systematic study of heredity, variations and factors responsible.
2.
Define heredity. Heredity is the inheritance of parental characteristics by their off springs.
3.
Mention the reasons as to why Mendel selected pea plants for his experiments. a) Pea plants can be grown easily in open ground or even in pots. b) They have a short growth period and life cycle. c) They give self-pollinating flowers and also it is easy to conduct cross pollination artificially. d) They produce large number of seeds. e) They show contrasting heritable characters. f) They produce fertile hybrids on cross pollination.
4.
Mention the seven contrasting characteristics considered by Mendel in his experiments. Character
5.
Contrasting forms
1
Stem length
Tall
Dwarf
2
Seed colour
Yellow
Green
3
Shape of the seed
Round
Wrinkled
4
Colour of the seed coat
Grey
White
5
Colour of the pod
Green
Yellow
6
Nature of the pod
Inflated
Constricted
7
Position of the flower
Axial
Terminal
How did Mendel obtain pure or true breeding varieties of the contrasting forms of pea plants? Mendel obtained pure or true breeding varieties of pea plants by allowing them to self pollinate for several generations.
6.
What is meant by monohybrid cross? A cross between two plants which differ in one specific character is called monohybrid cross.
7.
What is meant by F 1 or first filial generation? The plants obtained by Mendel by cross pollinating plants Mendel collected the seeds of the cross pollinated plats and sowed them in the next season. The plants obtained were called as F 1 or first filial generation.
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What is meant by F 2 or second filial generation? Mendel planted the F 1 generation seeds. When the plants flowered, he allowed them to self pollinate. He collected and sowed the seeds. The plants which germinated were called the F 2 or second filial generation.
9.
What is monohybrid cross ratio?
10.
The ratio obtained in the F 2 generation by crossing of two different traits of a single character is called monohybrid cross ratio. It is 3:1 What is meant by dominant trait/factor? The factor which expresses itself in the generations is called dominant trait/factor. Example: In the F 2 generation of pea plants, the factor for tallness is called as dominant factor.
11.
What is meant by recessive trait/factor? The factor which remains hidden or concealed in the generations is called recessive trait/factor. Example: In the F 2 generation, the factor for dwarfness remained hidden so it is called recessive factor.
12.
Give reason: a) Tallness is called dominant factor in the F2 generation of pea plants. In the F2 generation tallness was the factor which expressed hence it is called the dominant factor. b) Dwarfness is called recessive factor in the F2 generation of pea plants. In the F2 generation dwarfness was hidden or concealed, hence it is called the recessive factor.
13.
State Mendel’s principle of dominance. “When two factors responsible for a pair of contrasting forms of a single character come together, normally one expresses itself, while the other does not”.
14.
Mendel crossed a tall plant with a dwarf plant. Write a checker board/Punnet squares to represent the result obtained in F 2 generation.
15.
Draw the checker board to represent crossing the plants grown from pure round (RR) seeds with plants grown from pure wrinkled (rr).
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16.
What is phenotype? The character expressed by an organism or the observable characteristics of an organism is called phenotype.
17.
Write the phenotypic ratio of monohybrid cross. 3:1 (3 tall & 1 dwarf)
18.
What is genotype? The genetic characteristics of an organism are called genotype.
19.
Write the genotypic ratio of monohybrid cross. 1:2:1 ( 1 pure tall, 2 tall & 1 pure dwarf)
20.
Differentiate between phenotype and genotype. Phenotype The character expressed by an organism
Genotype The genetic characteristics of an organism
It is 3:1 for monohybrid cross It is 1:2:1 for monohybrid cross 21.
What is dihybrid cross? A cross between two plants which differ in two specific characters is called dihybrid cross.
22.
What is dihybrid cross ratio? The ratio obtained in the F 2 generation by crossing of two different traits of two characters is called monohybrid cross ratio. It is 9:3:3:1
23.
Mendel crossed a tall plant with red flowers with a dwarf plant with white flowers. Write a checker board/Punnet squares to represent the result obtained in F 2 generation.
24.
Write the phenotype ratio with the types of plants produced in Mendel’s dihybridisation experiment. The phenotype ratio is 9 : 3 : 3 : 1
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The type of plants used by Mendel was Tall plant with red flowers and dwarf plants with red flowers. 25.
State Mendel’s law of segregation or law of purity of gametes. “The pair of factors for a given character separates in equal ratio at the time of gamete formation during meiosis”.
26.
Explain Mendel’s law of segregation. The two pairs of factors separate during the formation of gametes. They do not blend but separate into different gametes. The gametes combine together by random fusion at the time of gamete formation.
27.
State Mendel’s law of Independent Assortment. “Factors controlling separate characters normally move independent of each other during gamete formation.”
28.
Explain Mendel’s law of Independent Assortment. Combinations of characters which are not present in the parental forms are produced in the next generation. When there are two pairs of contrasting characters, the distribution of the members of one pair into the gametes is independent of the distribution of the other pair.
29.
What is meant by Mendelian type of inheritance? When the results of hybridization experiments are similar to that of Mendel’s experiment then it is called Mendelian type of inheritance.
30.
What is incomplete dominance? Illustrate and explain Carl Correns experiment of incomplete dominance. When the results of monohybrid cross and dihybrid crosses do not follow the Mendel’s principles then it is called incomplete dominance. Carl Correns conducted hybridization experiments using the Four ‘O clock plant. He crossed a homozygous plant with red flowers (RR) with another homozygous plant with white flowers (ww). The F1 generation produced all plants with only pink flowers. This was deviation from Mendelian inheritance. This is called incomplete dominance.
31.
Name the type of plants obtained by Carl Correns experiment and write the phenotype ratio. Carl Correns selected Four ‘O clock plant with red flowers and white flowers. In the F1 generation he obtained all pink flowers. In the F2 generation he obtained red, pink and white flowers in the ratio 1:2:1.
32.
Write a schematic representation of monohybrid cross of 4’O clock plant with red flowers (R) and white flowers (W) Gametes
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W
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F1 Generation F2 Generation RR, 33.
34.
RW (Pink) RW, RW,
WW
(Red), (Pink), (Pink), (White) Draw the checker board to represent crossing the 4’O clock plant with Red flowers (r) and white flowers (W)
Explain why there is deviation in the F1 generation of the 4’O clock plants with red and white flowers. Red colour is expressed only in homozygous condition and the white colour is also expressed only in homozygous condition. But in heterozygous condition both the genes express. Hence intermediate pink coloured flowers are produced.
35.
Differentiate between homozygous and heterogyous plants. Homozygous The condition in which a single trait or
Heterozygous The condition in which a trait or
character with both the factors same (RR) character with different factors (RW) 36.
Write the structure of chromosomes. A nucleus has long, diffused and thin thread like structure called chromatin thread or chromatin network in the nucleoplasm. Chromosomes are made of two main substances proteins and nucleic acids.
37.
What are chromatids? The two parallel stands of chromosomes are called chromatids.
38.
What is centromere? The chromatids are held together by centromere.
39.
What are genes? The thousands of hereditary units in the DNA molecule are called genes.
40.
Explain the Watson - Crick Model of DNA. The structure of DNA molecule resembles a spirally twisted ladder called double helix. It has a pair of polynucleotide chain running anti-parallel (run parallel to each other but with opposite alignments) to each other. Each polynucleotide unit consists of Deoxyribose sugar, phosphate and a nitrogenous base. The Deoxyribose sugar is a pentose sugar (C 5 H 10 O 5 ). Each strand of the ladder is made up of Deoxyribose sugar and phosphate arranged alternatively. The nitrogenous bases connect the two opposite strands like the rungs of a ladder.
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41.
What are nucleotides composed of?
42.
Each polynucleotide unit consists of Deoxyribose sugar, phosphate and a nitrogenous base. What are purines and pyramidines? Nitrogenous bases Adenine (A) and Guanine (G) are called purines. Nitrogenous bases Cytosine (C) and Thymine (T) are called pyramidines.
43.
Name the nitrogenous bases in a DNA molecule. The four nitrogenous bases are Adenine (A), Guanine (G), Cytosine (C) and Thymine (T).
44.
What is meant by complimentary base pairing? The pairing of Adenine (A) with Thymine (T) and Guanine (G) paring with Cytosine (C) is called complimentary base pairing.
45.
Give reason: The two strands of DNA molecule are complementary to each other but are not identical. The two strands of DNA are not identical because the nitrogenous bases are different in pairing. A purine base of one polynucleotide chain always pairs with a pyramidine base on the other. Adenine (A) pairs with Guanine (G) and Cytosine (C) pairs with Thymine (T). Hence the two strands of DNA are complementary.
46.
Give reason: Genetic material present in the mother cell must get doubled. The daughter cells produced by cell division must receive the same genetic materials in same quantity so as to resemble the parent cell. Hence the genetic material present in the mother cells must be doubled.
47.
What is meant by DNA replication? DNA replication is the process of producing two identical replicas from one original DNA molecule.
48.
Briefly explain DNA replication. DNA replication is the process of producing two identical replicas from one original DNA molecule. The process of replication begins with the breaking of hydrogen bonds between the nitrogenous bases of complementary nucleotide strands. The two unwound strands of DNA helix serves as templates for the assembly of new but complementary nucleotides to form the daughter strands. The assembly of nucleotides on the parent DNA template is brought about by some enzymes.
49.
‘Replication of DNA is a significant phenomenon’. How? Replication of DNA ensures equal distribution of the genetic material to the future daughter cells.
50.
Mention the significance of DNA. a) DNA has the coded information for controlling all the metabolic activities of the cell both directly and indirectly.
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b) By the property of self replication, it ensures the equal distribution of similar genetic material to off springs and thus responsible for heredity. c) DNA indirectly helps in protein synthesis. d) DNA sometimes undergoes mutation and recombination which brings about variations in the characters of the off springs. 51.
What is meant by mutations? Any change in the structure or composition of genetic materials such as gene or chromosomes is called mutation.
52.
Mention the types of mutations. How do they occur? Mutations are of two types – gene mutation and chromosome mutation. Gene mutation can occur naturally or it can be induced. Mutations are due to change in the base sequence of DNA.
53.
What is the significance of DNA technology? Knowledge of DNA technology has led us to study the possibilities of many genetically related physical and physiological problems. Knowledge of DNA technology helps in improving the quality of plants and animals. It helps even to obtain materials from plants and animal species for the human benefit. It has applications in the field of agriculture, health, food management, conservation of environment etc.
54.
What is meant by biotechnology? The application of technological procedures on organisms or their processes or their products to obtain new substances for human welfare is called biotechnology.
55.
What is meant by genetic engineering? The technique of inducing desirable changes in the genetic material such as DNA of an organism is called genetic engineering.
56.
What is meant by recombinant DNA technology? The technique of manipulating the genes in the laboratory is called recombinant DNA technology. It involves the separation of desirable or useful gene from a cell and introduce it into another cell where it is made to express.
57.
Mention one application of recombinant DNA technology. Recombinant DNA technology is used to transfer nitrogen fixing gene from bacteria into plants which enable them to get nitrogen.
58.
Mention any two applications of recombinant DNA technology in a) Animals breeding b) Plant breeding Recombinant DNA technology is used for improving the quality of animal breeds. It is used to transfer nitrogen fixing gene from the bacteria into plants to enable them to obtain nitrogen.
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What is meant by DNA finger print technology? The technique in biotechnology used for identifying individuals by determining the genetic relationships is called DNA finger print technology.
60.
Explain DNA finger print technology. The technique in biotechnology used for identifying individuals by determining the genetic relationships is called DNA finger print technology. The technique involves breaking down the DNA of individual into short segments using specific enzymes. The fragments get separated on the basis of size and net electrical charge. They get arranged to form a finger print.
61.
What is gel electrophoresis? The technique of breaking down the DNA of individual into short segments using specific enzymes is called gel electrophoresis.
62.
Write the importance of gel electrophoresis during DNA finger print technology. Gel electrophoresis helps to break down the DNA of an individual into short fragments from which a DNA finger print can be obtained.
63.
On what basis the short fragments of DNA arrange themselves? The short fragments of DNA get separated on the basis of their size and net electrical charge.
64.
What is DNA finger print? The series of bands in the form of fingerprint with a unique pattern is called DNA finger print.
65.
What is meant by cloning? The technique of obtaining genetically similar molecules, cells, tissues or organism from a common precursor invitro process is called cloning.
66.
What is a clone? The group of molecules or cells or organism which is derived from the same parent by an asexual process is called a clone.
67.
Name the first clone and the person who developed it? The first clone was a sheep called Dolly. It was developed by Dr.Wilmut.
68.
Mention the applications of biotechnology. a) Biotechnology helps in large scaled synthesis of life saving drugs like antibiotics, vaccines, artificial hormones. b) It helps in improvement of plant and animal breeds, pests and pathogen control in agriculture.
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c) It helps in the synthesis of acceptable additives (preservatives, colouring agents and artificial flavours) in food processing and management industries. d) It is used in synthesis of biocatalyst & biopolymers. e) It is used in pollution control, sewage treatment and water recycling. f) It is used to transfer nitrogen fixing gene from bacteria into plants which enable them to get nitrogen.
69.
Give reason: Though biotechnology is a boon to mankind, it may cause serious threat in future. OR Mention the limitations of biotechnology. a) The use of biotechnology in plants has resulted in seed sterility which causes severe threat to the conservation of plant species. b) Genetically modified foods are a threat to human and animal health. c) It is against nature and upset the delicate balance of the nature. d) Cloning pose a very serious social, ethical, moral and cultural problems. e) Cloning can be used for illegal purposes and destructive activities.
70.
Production of genetically modified plants is both a boon and bane. Explain. By genetically modifying plants we can increase the yield, improve the plant breeds, make them pest and disease resistant. We can also transfer nitrogen fixing gene. The greatest disadvantage of genetically modified plants is the sterility of seeds which is a threat to conservation of plant species.
Fill in the blanks: 1.
The branch of biology which deals with a systematic study of heredity, variations and factors responsible is called genetics.
2.
The inheritance of parental characteristics by their off springs is called heredity.
3.
The ‘Father of modern genetics’ is Gregor Johann Mendel.
4. 5. 6.
The reproductive structure of a plant is flower. A cross between two plants which differ in one specific character is called monohybrid cross. The ratio of monohybrid cross in F2 generation is 3:1.
7.
Mendel called the factor which showed in the generations as dominant factor.
8.
Mendel called the factor which is hidden or concealed in the generations is called recessive factor.
9. 10.
The character expressed by an organism is called phenotype. The genetic characteristics of an organism are called genotype.
11.
The phenotype ratio of monohybrid cross is 3:1.
12. 13.
The genotype ratio of monohybrid cross is 1:2:1. The cross between two plants which differ in two characters is called dihybrid cross.
14.
The ratio of dihybrid cross is 9:3:3:1.
15.
The pair of factors for a given character separates in equal ratio at the time of gamete formation during meiosis is Mendel’s law of segregation.
16.
Mendel’s law of segregation is also called law of purity of gametes.
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17.
Factors controlling separate characters normally move independent of each other during gamete formation is Mendel’s law of independent assortment.
18.
The type of dominance which deviates from the Mendelian inheritance is called incomplete dominance.
19.
The genetist who proposed incomplete dominance is Carl Correns.
20.
Carl Correns used 4’O clock plants for his experiments on incomplete dominance.
21.
The condition in which a single trait or character with both the factors same is called homozygous.
22.
The condition in which a trait or character with different factors is called heterozygous.
23.
The two parallel stands of chromosomes are called chromatids.
24.
The chromatids are held together by centromere.
25.
The thousands of hereditary units in the DNA molecule are called genes.
26.
Polynucleotide unit consists of Deoxyribose sugar, phosphate and a nitrogenous base.
27.
Nitrogenous bases Adenine (A) and Guanine (G) are called purines.
28.
Nitrogenous bases Cytosine (C) and Thymine (T) are called pyramidines.
29.
The pairing of Adenine (A) with Thymine (T) and Guanine (G) paring with Cytosine (C) is called complimentary base pairing.
30.
The process of producing two identical replicas from one original DNA molecule is called DNA replication.
31.
Any change in the structure or composition of genetic materials such as gene or chromosomes is called mutation.
32.
The application of technological procedures on organisms is called biotechnology.
33.
The technique of inducing desirable changes in the genetic material such as DNA of an organism is called genetic engineering.
34.
The technique of manipulating the genes in the laboratory is called recombinant DNA technology.
35.
The technique in biotechnology used for identifying individuals by determining the genetic relationships is called DNA finger print technology.
36.
The technique of breaking down the DNA of individual into short segments using specific enzymes is called gel electrophoresis.
37.
The short fragments of DNA get separated on the basis of their size and net electrical charge. The series of bands in the form of fingerprint with a unique pattern is called DNA finger print.
38. 39.
The technique of obtaining genetically similar molecules, cells, tissues or organism from a common precursor invitro process is called cloning.
40.
The first clone was a sheep called Dolly.
41.
The first clone Dolly was produced by Wilmut.
42.
The greatest application of DNA finger print technology is in the filed of forensic science.
43.
One of the greatest applications of biotechnology is in the production of artificial hormones.
44.
One of the disadvantages of biotechnology in plants is sterility of seeds.
*****
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Chapter 22: Ionic Conduction
C22
1. Name the two types of electric conduction. The two types of electrical conduction are:
2.
a)
Electric conduction due to flow of delocalised electrons.
b)
Electrical conduction due to flow of ions.
What is electronic conduction? The type of conduction which is due to the flow of delocalised electrons is known as electronic conduction.
3.
What is electrolytic conduction? The type of conduction in which cations and anions participate in the flow of electricity in molten state or aqueous solution of salt is called as electrolytic conduction.
4.
What is meant by electrolytic solutions? The aqueous solutions in in which chemical reactions occur when direct current is passed are called electrolytic solutions.
5.
What is an electrolyte?
6.
The chemical substances that conduct electricity in aqueous state or molten state are called electrolytes. State the types of conduction of electricity. a) Metallic conduction b) Electrolytic conduction
7.
Give examples of substances through which metallic conduction occur. a) All metals Ex: Iron, Aluminium, Copper, Mercury etc. b) All alloys Ex: Brass, Bronze, and Steel etc. c) Graphite
8.
Give examples of substance through which electrolytic conduction occurs. a) Salts in molten state Ex: Sodium chloride, Calcium chloride, lead bromide etc. b) Aqueous solutions of sodium sulphate, copper sulphate etc. c) Bases Ex: Sodium hydroxide, Potassium hydroxide etc.
d) Aqueous solutions of acids Ex: Hydrochloric acid, sulphuric acid etc. 1. Mention the differences between metallic conduction and electrolytic conduction. Metallic conduction
Electrolytic conduction
1. It is a physical change
1. It is a chemical change
2. Only electrons conduct electricity
2. Positive and negative ions conduct electricity
3. All metals and metallic alloys exhibit metallic conduction.
3. Ionic compounds exhibit electrolytic conduction in aqueous solution.
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How are electrolytes classified? Electrolytes can be classified into: a) Strong electrolytes b) Weak electrolytes c) Non electrolytes
3.
What are strong electrolytes? Give example Electrolytes that dissociate almost completely are called strong electrolytes. Ex: Ionic compounds like Sodium chloride, copper sulphate, covalent compounds, hydrochloric acid, nitric acid, sulphuric acid.
4.
What are weak electrolytes? Give example Electrolytes that dissociate partially are called weak electrolytes. Ex: Vinegar, carbonic acid, phosphoric acid and organic acids like acetic acid, formic acid etc.
5.
What are non-electrolytes? Give example Substances which do not conduct electricity are called non-electrolytes. Ex: Sugar solution, distilled water etc.
6.
Observe the diagram alongside and answer the questions. a) When the electrodes are dipped in aqueous solution of sodium chloride. What do you observe? We observe the bulb glows brightly as sodium chloride is a strong electrolyte. b) When the electrodes are dipped in vinegar solution. What do you observe? We observe the bulb glows faintly as vinegar is a weak electrolyte c) When electrodes are dipped in sugar solution. What do you observe? We observe the bulb does not glow as sugar solution is a non-electrolyte.
7.
State Arrhenius theory of dissociation. “The molecules of an electrolyte in aqueous solution break into ions”
8.
What are ions? A group of charged atoms are called ions.
9.
What are anions? Anions are a group of atoms that have gained electrons. They have a negative charge.
10.
What are cations? Cations are atoms that have lost an electron to become positively charged.
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11.
Draw a neat diagram of the apparatus used in the electrolysis of copper chloride solution.
12.
In the electrolysis of copper chloride, write the equation which takes place at the a) cathode b) anode. +2e a) At cathode: Cu 2+ → Cu ↓
−
−e
b) At anode: Cl → Cl
→ Cl 2 Cl + Cl 13.
State Faraday’s first law of electrolysis. “The mass of substance deposited or collected at either electrode during electrolysis is proportional to the current and to the time”.
14.
Write the mathematical form of Faraday’s first law of electrolysis. M ∝ It M = Zit or M=ZQ where Q=It
15.
What is electro chemical equivalent? Electro chemical equivalent is defined as the mass in grams liberated by one Ampere of current in one second.
E.C.E =
16.
Mass of subs tance liberated Current x time
On what factors does the amount of deposition in electrolysis depend? The amount of deposition depends on the a) Current b) Time c) Nature of substance
17.
State Faraday’s second law of electrolysis.
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“The masses of different substances liberated by the same quantity of electricity are proportional to their chemical equivalents”. Define chemical equivalent. Chemical equivalent is defined as the ratio of atomic mass to its valency.
Chemical Equivalent =
19.
Atomic Mass Valency
Write the mathematical form of Faraday’s second law of electrolysis.
MA E A E = = F or = Cons tan t Z MB EB 20.
Define Faraday’s constant. Faraday’s constant is defined as the ratio of chemical equivalent to electrochemical equivalent of a substance.
21.
Write the value of Faraday’s constant. The value of Faraday’s constant is 96,500 coulomb/mole.
22.
Mention the applications of electrolysis. a) Electroplating b) Electrotyping c) Purification of metals d) Decomposition of salts e) Electro polishing f) Manufacture of certain chemicals like caustic soda.
23.
What is electroplating? Electroplating is the process of plating one metal onto another by passing current through the electrolyte.
24.
What is the aim of electroplating? The aim of electroplating is to give the articles made of one metal a coating of another metal either to improve the appearance or to protect it against rusting and tarnishing.
25.
Draw a neat diagram of apparatus used to electroplate a brass article with silver.
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What is electro polishing? Electro polishing is an electrochemical process that removes material from a metallic article. It is the reverse of electroplating.
27.
Explain electro polishing. The article to be electro polished is taken as anode in the electrolytic bath with copper or lead cathode and a suitable electrolyte. When direct current is passed through the electrolyte, the metal is removed from the anode by the action of current. Thus the anode is electro polished. Ex: Sandwiched cookers are manufactured by the electro polishing method.
28.
What mass of copper is deposited at the cathode in the copper voltameter by the passage of 2 amperes of current for 30 minutes?
29.
How many amperes of current is required to deposit on cathode 5g of gold per hour? (E.C.E of the gold is equal to 0.000681g/coulomb)
30.
How much time is required to deposit 1.1g of copper by passing 0.5 ampere of current? (E.C.E of copper is 0.00033 g/coulomb)
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31.
To deposit 0.54g copper on cathode in a copper voltameter, how much quantity of electricity is required? (E.C.E of copper is 0.00033 g/coulomb)
32.
Silver voltameter and copper voltameter are connected in series. The amount of silver and copper deposited are 0.31g and 0.091g respectively. If the E.C.E of copper is 0.00033 g/coulomb. Calculate the E.C.E of silver.
Fill in the blanks: 1.
The type of conduction which is due to the flow of delocalised electrons is known as electronic conduction.
2.
The type of conduction in which ions participate in the flow of electricity is called as electrolytic conduction.
3.
The aqueous solutions in which chemical reactions occur when direct current is passed are called electrolytic solutions.
4.
The chemical substances that conduct electricity in aqueous state or molten state are called electrolytes.
5. 6.
Metallic conduction is a physical change. Electrolytic conduction is a chemical change.
7.
An example of an electrolytic conductor is Sodium chloride.
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8. 9.
Electrolytes that dissociate almost completely are called strong electrolytes. An example of a strong electrolyte is copper sulphate.
10. 11.
Electrolytes that dissociate partially are called weak electrolytes. An example of a weak electrolyte is phosphoric acid.
12.
Substances which do not conduct electricity are called non-electrolytes.
13.
An example of a non-electrolyte is distilled water.
14.
According to Arrhenius theory of dissociation - The molecules of an electrolyte in aqueous solution break into ions.
15.
A group of charged atoms are called ions.
16.
A group of atoms that have gained electrons are called anions.
17.
A group of atoms that have lost an electron to become positively charged are called cations.
18.
The mass of substance deposited or collected at either electrode during electrolysis is proportional to the current and to the time.
19.
Mathematical form of Faraday’s first law of electrolysis is M ∝ It or M = Zit.
20.
The mass in grams liberated by one Ampere of current in one second is called Electro Chemical Equivalent (E.C.E).
21.
The masses of different substances liberated by the same quantity of electricity are proportional to their chemical equivalents.
22.
The ratio of atomic mass to its valency is called Chemical equivalent.
23.
A The mathematical form of Faraday’s second law of electrolysis is =
M MB
EA = F EB
24.
The ratio of chemical equivalent to electrochemical equivalent of a substance is called Faraday’s constant.
25.
The value of Faraday’s constant is 96,500 coulomb/mole.
26.
The process of coating one metal onto another by passing current through the electrolyte is called electro plating.
27.
The aim of electroplating is to improve the appearance or to protect it against rusting and tarnishing.
28.
The electrochemical process that removes material from a metallic article is called Electro polishing.
29.
The process of electro polishing is the reverse of electroplating.
30.
The article to be electro polished is taken as anode.
*****
Chapter 23: The story of Humans 1.
B23
What were the contributions of Charles Darwin? a) Charles Darwin gave the most accepted explanation for the mechanism of organic evolution. b) He suggested that human beings evolved from monkeys. c) He noticed similarities between man and apes. d) He also suggested that man, apes and monkeys have a common ancestor.
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Write the classification of humans. Humans belong to:
3.
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens
What are the characteristics that humans share with other primates? a) Primates have a distinct face in place of snout. b) Most of the skull is posterior to the eyes. c) Eyes are directed forward, enabling binocular vision. d) Free movement of the digits, especially the opposing thumb. e) Claws are modified into nails. f) Enlarged brain, especially the cerebral hemispheres. g) Only two mammary glands to nourish young ones. h) Generally only one offspring in each pregnancy.
4.
What are the features of Dryopithecus?
5.
Dryopithecus had strong muscular arms that were longer than the legs. They were found in certain parts of Europe and China. What are the characteristics of Zinjanthropus? a) Zinjanthropus occurred about 14 to 15 million years ago. b) They developed stronger and straighter legs with feet suited for walking. c) They could focus their eyes on objects which they were holding. d) They had stereoscopic vision and acute hearing mechanism. e) They started using their grasping hands for various purposes. They were also able to manipulate objects with the help of flexible hands. f) There was enlargement of cerebrum.
6.
What were the changes that led to the upright posture of man? The upright posture of Zinjanthropus was the result of evolutionary changes in the pelvic girdle and associated muscles. The pelvic girdle changed into a broad basin like structure to support the trunk.
7.
The second change which led to upright posture was the change on the skull. The hole in the skull through which the brain continues got shifted to the lower surface. Write a note on Ramapithecus. Ramapithecus lived about 13 to 14 million years ago. They were the descendents of prehuman who appeared in Siwalik range of India. They are considered as the true ancestor of modern man. They were widely distributed in both Australia and Africa.
8.
What factors accelerated the evolution of early ancestors? a) Shift in the earth’s crust
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b) Severe change in climate which resulted in the conversion of large forests into grasslands. 9.
Who were Australopithecus? The descendent of Ramapithecus who appeared 5 million years ago in the drier regions of Eastern and Southern Africa were known as Australopithecus.
10.
What were the characteristics of Australopithecus? a) Australopithecus were the descendent of Ramapithecus who appeared 5 million years ago in the drier regions of Eastern and Southern Africa. b) They were relatively short (four and a half feet in height) c) The forehead was low. d) The brain capacity was equal to that of the modern gorilla. e) The cranial capacity was about
1
rd of modern man.
3
f) They walked erect. g) They hunted in groups h) They used pebbles and bones as tools. 11.
What are the characteristics of Homo habilis? Homo habilis evolved from Australopithecus. Their cranial capacity was about 700 cc. The limb bones resembled almost that of modern man. They used tools and weapons.
12.
Write about Java man and Peking man. The form of Homo erectus which was discovered in Java in Indonesia is called Java man.
13.
The form of Homo erectus which was discovered in Peking in China was called Peking man. How do we know that Peking man was using fire?
14.
The occurrence of charcoal along with the fossils suggested that Peking man was using fire. What are the characteristics of Homo sapiens? a) Homo erectus were by Homo sapiens about 2,50,000 years ago. b) They had a larger brain capacity then their ancestral forms. c) Their intellectual capacity was much higher. d) They had also developed language. e) They used sophisticated tools and weapons.
15.
Who was the Neanderthal man? The earliest form of Homo sapiens was known as Neanderthal man.
16.
Write the characteristics of Neanderthal man. a) Neanderthal man was the earliest form of Homo sapiens. b) They appeared in Eurasia and Northern Africa.
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c) They were rather short, heavily built and strong. d) They had heavy brow ridges. e) The fore head was sloping with small chin and protruding jaws. f) He was good in making tools. g) He also developed speech. 17.
What led to the disappearance of Neanderthal man? Neanderthal man disappeared about 50,000 years ago during the last glaciations. They were also exterminated by men who overpowered them. They were unable to compete with a culturally more advanced group of men, armed with better tools and weapons.
18.
Who were Cro-Magnon men? The group of early men who replaced the Neanderthal man were known as Cro-Magnon men.
19.
What are the characteristics of Cro-Magnon men? a) Cro-Magnon men lived about 30,000 years ago around the end of ice age. b) They had a large stature. c) They were active and intelligent. d) They had association with animals. e) They used finely chipped stone arrows and spear points. f) They carved tools and ornaments from ivory.
20.
How is modern man different from Cro-Magnon man? a) Culturally modern man is more advanced. b) He is capable of thinking, memorizing, speaking, reading and writing. c) He developed agriculture and started domesticating animals. d) He has also learnt to manipulate nature according to his needs. e) He has developed science and technology using his intelligence. f) He has emerged as the most dominant creature on earth.
21.
What is meant by stock or race? A classification system used to categorize humans into large and distinct populations.
22.
Name the five human races. a) Caucasoids b) Mongoloids c) Congoids d) Capoids
23.
e) Australoids Briefly explain the characteristics of the five races. 1) Caucasoids a) They are characterized by light skin. b) They have blue or dark brown eyes.
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c) They have a high ridged nose with narrow nostrils. d) Hair is straight or wavy. e) They live in Europe, India and certain parts of America. 2) Mongoloids a) They are characterized by yellowish or reddish skin. b) They have thick lip and wider nose. c) Hair is straight. d) They live in China, Japan, Mongolia, Malaysia, American Indians and Eskimos. 3) Congoids a) They are characterized by black skin. b) They have thick lip and wider nose. c) Hair is woolly d) They live in Central and South Africa. 4) Capoids a) They are characterized by black or brown skin. b) They are represented by bushmen of Africa. 5) Australoids a) They are characterized by brown skin. b) Hair is curly. c) They have deep eye sockets. d) They are the original inhabitants of Australia.
Fill in the blanks: 1. 2. 3.
The theory of natural selection was proposed by Charles Darwin. The person who suggested that human beings evolved from monkeys was Charles Darwin. The book published by Charles Darwin is ‘The Descent of Man’.
4.
‘The Descent of Man’ is the book published by Charles Darwin.
5.
The similarities between man and apes were noticed by Charles Darwin.
6.
The person who suggested that man, apes and monkeys have a common ancestor was Charles Darwin.
7.
Man, apes and monkeys have a common ancestor.
8. 9.
The genus to which humans belong is homo. The family to which humans belong is Hominidae.
10. 11.
The order to which humans belong is Primates. The group to which humans are classified under mammals is called primates.
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12.
Most reliable and direct evidence for evolution comes from the study of fossils.
13.
Apes and humans have evolved from a semi erect terrestrial from of primates called proconsul.
14.
The ancestors of modern apes like orangutan and gorilla have evolved from Dryopithecus.
15.
The arrival of upright pre human form appeared about 14 to 15 million years ago.
16. 17.
The first upright pre human form was named Zinjanthropus. The upright posture was a result of evolutionary change in pelvic girdle.
18.
The true ancestor of modern man was called Ramapithecus.
19.
The fossil remains of Ramapithecus have been recovered from Siwalik range.
20. 21.
The pre-human form considered to be the first humans were Australopithecus. The oldest known fossil skull of genus homo was called Homo habilis.
22.
Homo habilis evolved into more modern form of humans called Homo erectus.
23.
Homo erectus lived about 2,50,000 years ago.
24. 25.
The earliest form of Homo sapiens is known as Neanderthal man. The fossil of the earliest form of Homo sapiens was discovered in Neanderthal valley.
26.
The Neanderthal men were replaced by a group of men called Cro-Magnon men.
27.
The sub divisions of human species are called stock or race. *****
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Chapter 24: Space Science
P24
(A) Stars & Galaxies 1.
What is meant by stellar evolution? The process from the birth to the death of a star is called stellar evolution.
2.
What is a protostar? A protostar is a large mass that forms by contraction of the gas mostly hydrogen.
3.
How is a protostar formed? OR How is a star born? The birth of a star begins when a gaseous cloud of hydrogen contracts due to gravity. The gaseous cloud contracts due to its own gravity. As the cloud contracts, there is increase in density which leads to increase in pressure. Gradually a spherical mass is formed at the centre of the cloud.
4.
How does a protostar attain a steady state? When a protostar continues to contract, its temperature increases to millions of degrees. The density at the centre increases as the matter is compressed. When the temperature reaches about 10 million Kelvin, some of the hydrogen nuclei fuse to form Helium nuclei producing large quantity of heat, light and radiation. The force acting outwards and the gravitational pull balances it. Thus the star reaches a steady state.
5.
In which stage is the Sun? Sun has been in the steady stage for about five billion years.
6.
How does a star change from steady state to red giant stage? OR Briefly explain how a red giant is formed. A star on reaching the steady state will start giving out steady energy. As the radiation pressure increases beyond the opposing gravitational pull, the star begins to swell. As a result of this the temperature decreases and hence emits red light. This stage of star is called Red giant.
7.
Briefly explain the formation of planetary nebula. After the red giant stage the star envelope expands, the core contracts, the temperature reaches 108 Kelvin. Helium starts converting into carbon in the core. When all the helium gets converted to carbon, the core cannot contract further. Due to the outward force, the outer envelope gets detached and thrown out into space. This stage is called planetary nebula.
8.
Briefly explain the formation of white dwarf.
9.
If a star has a mass less than 1.4 times the mass of the sun, the star collapses under gravity. Due to the high temperature, the star glows with white light of high frequency. This stage is known as white dwarf. What is Chandrashekar’s limit? The value 1.4 times the mass of the sun is known as Chandrashekar’s limit.
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10.
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Write the contribution of S.Chandrashekar in the field of astronomy. Dr.S.Chandrashekar developed the theory of white dwarf and showed that if mass of a star is greater than 1.4 times the mass of the sun, its life will end by collapsing into a black hole.
11.
Name the stages of stellar evolution of sun like stars in the galaxy. Protostar → Steady state → Red giant → Planetary nebula → White dwarf
12.
Name the stages of stellar evolution of massive stars. Protostar → Steady state → Red giant → Supernova → Neutron star or Black hole
13.
Briefly explain the evolution of stars which are more massive than the sun. Stars which are 5 times more massive than the sun evolve in different way after the red giant stage. Several stages of nuclear reactions get ignited one after the other. The carbon nuclei produced during the fusion of helium forms carbon core. The carbon nuclei in the core fuse and liberate energy. Heavier elements like oxygen, magnesium and silicon. The fusion continues till element iron is formed. The star explodes as a supernova.
14.
What is a supernova? The explosion of a star that is 5 times or more massive than the sun is called supernova.
15.
What is a neutron star? How is it formed? A star whose core contains only neutrons is called neutron star. If the remnants of supernova condense to a core composed of tightly packed neutrons, then it becomes a neutron star.
16.
What is a pulsar? Fast spinning neutron stars emitting radiation in pulses are called pulsars.
17.
What are quasars? Quasar is the short form of “Quasi Stellar radio sources”. Quasars are galaxies that are thousand times brighter than ordinary galaxies which emit radiowaves.
18.
Briefly explain the evolution of stars which are 30 times the mass of the sun. OR What is a black hole? How is it formed? A black hole is a region of intense gravitational field. If a star has a mass of 30 times the mass of the sun, then the remnants of the supernova explosion compress into a very small region of intense gravitational field.
19.
What properties of a black hole can be recognized? Density and gravity of a black hole can be recognized.
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Why cannot the properties like temperature, pressure or chemical composition of black holes be determined? No information in the form of light or radio waves comes out of black hole. Hence we cannot determine the properties of a black hole except density and gravity.
21.
How is the presence of black holes detected? The presence of a black hole can be inferred from the gravitational force it exerts on bodies close to it.
22.
When can sun become a black hole? Sun would become a black hole if it is compressed to a radius of 3km.
23.
Why do stars differ in their colour? Stars differ in their colour because of different surface temperatures.
24.
On what factor does the colour of a star depend? Colour of a star depends on the surface temperature.
25.
How is the temperature of stars determined? Analysis of the lines of spectrum of a star helps us to identify the elements present in the star. The intensity distribution of these elements decides the apparent colour of the star.
26.
Write the temperature of the following stars and their colour. Betelgeuse, Arcturus, Sun, Sirius, Rigel
27.
Star
Temperature
Colour
Betelgeuse
2000K to 3500K
Red
Arcturus
3500K to 5000K
Orange yellow
Sun
5000K to 6000K
Yellow
Sirius
6000K to 10,000K
Yellowish white
Rigel
10,000 to 50,000K
Bluish white
What is a galaxy? A galaxy is a huge collection of stars held together by gravitational force.
28.
How can we know the information about the velocities of galaxies?
29.
The velocity of galaxies can be known by studying the spectral lines. What is the name of our galaxy? What type of galaxy is it? Our galaxy is called Milky Way. It is a spiral galaxy.
30.
Write short notes on Milky Way galaxy. a) Milky Way galaxy is a spiral galaxy. b) Its diameter is about one lakh light years. c) It appears like a flat disc with a central bulge when viewed from the edge. d) Its central thickness is 6000 light years.
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e) Sun is located about 28,000 light years from the centre. f) It takes about 250 million years to go around the centre of our galaxy. How are galaxies classified? The three fundamental types of galaxies are: a) Elliptical galaxy b) Spiral galaxy c) Irregular galaxy
32.
Differentiate between elliptical and spiral galaxy. Elliptical galaxy
33.
Spiral galaxy
They are relatively dim
They are bright
They are difficult to see
They are most beautiful to see
They have older stars
They have newly formed stars
What is the essence of big bang theory? Edwin Hubble, an American astronomer studied various galaxies and showed that the universe is expanding. At the beginning of the universe, all the matter comprising of stars and galaxies were compressed into a fiery ball. The fire ball exploded with a bang which started the expansion of the universe. This is the essence of big bang theory.
34.
What is the evidence for the expanding universe? The red shift of galaxies shows that they are moving away from us at enormous speeds.
35.
State Hubble’s law. The velocity of recession of a celestial body is proportional to its distance from us
36.
Which are the two factors that are related to one another according to Hubble’s law? Velocity of celestial bodies and distance from earth.
(B) Rockets & Artificial Satellites 37.
How is a rocket different from an aircraft? Aircraft uses oxygen in the atmosphere where as a rocket has to carry the necessary oxidizer to burn the fuel.
38.
How are rockets able to operate in space? Rockets are able to operate in vacuum or space as they carry oxidizer to burn the fuel.
39.
What is an oxidizer? The substance that provides oxygen to burn the fuel is called oxidizer.
40.
What is a propellant?
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The mixture of oxidizer and fuel is called propellant. 41.
Name some rocket propellants. a) Liquid hydrogen & liquid oxygen b) Kerosene & liquid oxygen c) Hydrazine & nitric acid d) Synthetic rubber & liquid oxygen e) Cellulose base compound & liquid oxygen f) Polybutadiene& acrylic acid with aluminium percolate
42.
On what principle does the launching of rocket work? Launching of rocket works on the principle of Newton’s Third law of motion & the law of conservation of momentum.
43.
State the principle of conservation of momentum. The total momentum of the system is conserved when the net force acting on the system is zero.
44.
Explain how the principle of conservation of momentum is involved in rocket working. During firing of rocket, the fuel burns & is converted into gases at high pressure. The gases escape from the nozzle of rocket with a high velocity. The rocket acquires an equal momentum in opposite direction.
45.
Define payload. The scientific instruments which is usually placed in the front region of the rocket is called payload.
46.
State the factors on which the acceleration of rocket depends. a) Amount of fuel burnt b) Exhaust velocity c) Mass of the rocket
47.
Define thrust on the rocket. Thrust on the rocket is the product of rate of fuel consumption and velocity of exhaust gases. Thrust = Rate of fuel consumption x Exhaust velocity Thrust = R x V ex
48.
Mention the practical aspects to be considered while launching a rocket. a) As the rocket consumes fuel every instant, its mass goes on decreasing.
49.
b) The acceleration due to gravity changes continuously as the rocket ascends. c) The atmosphere offers resistance in the lower layers of atmosphere. Define payload ratio.
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The ratio of payload mass (m) to the ratio of the fuel mass (M) is called payload ratio.
Payload ratio = 50.
Payload mass m = Fuel mass M
Explain the parts of a single stage rocket. A single stage rocket consists of: a) Payload – The scientific instruments placed in the front portion of rocket. b) Propellant – Fuel & oxidizer is called propellant. c) Valves – The quantity of propellant reaching the engine is controlled by the valves. d) Engine – It is the most important part of a rocket. It is a chamber where combustion of fuel takes place. e) Nozzle – Burning of fuel in the engine produced gases which escape at high pressure through the nozzle which in turn helps to lift the rocket.
51.
What is meant by streamlining of rocket? What is its function? The characteristic external shape of the rocket is called streamlining of rocket. Streamlining of rocket minimizes the friction of air. It also gives stability to the rocket when it moves in the earth’s atmosphere.
52.
Draw a neat diagram of a single stage rocket and label the parts.
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Define orbital velocity. The velocity of the satellite along a circular path is called orbital velocity. It is denoted by Vo.
54.
Derive an expression for the orbital velocity of a body revolving around the earth at a height ‘h’. We know that centripetal force Fcp = Gravitational force = Fg =
M Vo 2 -------------(1) R+h
GMm -------------------------------(2) (R + h)2
Vo 2 =
Equating (1) and (2) 2
M Vo GMm = (R + h) (R + h)2
GM (R + h)
Vo =
Where Vo=orbital velocity
GM (R + h)
Cross multiplying 2
2
MV o (R+h) = GMm (R+h) 55.
Write the formula for orbital velocity of an artificial satellite very close to the earth.
GM or Vo Vo == R 56.
G= Gravitational constant M=Mass of earth R=Radius of earth h=height above the surface of earth
= Rg where g
GM R2
Mention the factors on which the orbital velocity depends. a) Mass of the body b) Distance of the object from the center of the body.
57.
Give reason: A single stage rocket cannot be used to place satellites into orbit. A single stage rocket cannot lift the satellite to greater heights.
58.
What are multistage rockets? Several rockets joined one on top of another to provide the necessary power is called multistage rocket.
59.
Why are multistage rockets used to launch space vehicles? A single stage rocket cannot lift heavy load to a greater height. Hence multistage rockets are used.
60.
Explain the working of multistage rockets.
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A multistage rocket consists of several rockets joined together one on top of another. When a multistage rocket is launched, the first stage engine begins. After travelling a certain distance, the first stage detaches from the rocket system. The engine of the second stage begins. It carries the rocket to a certain height and detaches itself. Now the 3rd stage starts and so on. Generally first stage is massive and other stages are smaller.
61.
What are the advantages of multistage rockets? a) Multistage rockets reduce the fuel consumption slightly. b) Removal of each stage decreases the dead weight (empty tanks) of the system. c) They can carry heavy load to greater height. d) It increases the efficiency of the rocket.
62.
What is meant by escape velocity of earth? What is its value? The minimum velocity with which a body must be projected so that it escapes from the gravitational field of earth is called escape velocity. It is denote by Ve. The value of escape velocity is 11.2 km/s.
63.
What are the factors that the value of escape velocity?
64.
The escape velocity of an object from earth depends upon the radius of the earth and acceleration due to gravity and is independent of the mass of the object. Why does a slow moving object thrown upwards fall back to the earth?
65.
Slow moving objects fall back to earth because it cannot escape from the earth’s gravitational field. Write the formula for escape velocity.
Ve =
2R g , Where Ve= Escape velocity, R=Radius of earth and g=acceleration due to
gravity. 6
66.
Calculate the escape velocity for earth given (Radius of earth is 6.37x10 m and -2 acceleration due to gravity is 9.8ms )
67.
What happens when a stone is thrown upwards with a velocity of more than 11.2km/s? The stone would escape the earth’s gravitational field.
68.
Write the relation between orbital velocity and escape velocity. Orbital velocity = Vo =
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258
2R g
Substituting (2) in (1)
Ve =
2R g
Ve = 2 x Rg Ve = 2 Vo 69.
Is the escape velocity of moon greater than that on earth? Why? No, escape velocity of moon is less than that of the earth as mass of moon is less when compared to earth.
70.
What is a geostationary satellite? An artificial satellite having a period of revolution same as that of the period of rotation of the earth is called geostationary satellite.
71.
What is the main objective of launching geostationary satellites? Establishment of communication link.
72.
73.
Why is the period of revolution of geostationary satellite more or less than 24 hours? The period of revolution of satellite has to be the same as that of period of rotation of earth which is 24 hours. How many geostationary satellites are required to cover every part of the earth? Three geostationary satellites are required.
74.
At what height should a satellite be placed to make a satellite geostationary? Geostationary satellites must be placed 36,000km above the surface of the earth.
75.
Mention the orbital period and distance from the surface of the earth of geostationary satellites. Orbital period must be 24 hours. Distance from the surface of the earth must be greater than 36,000km.
76.
Mention the uses or applications of satellites. Artificial satellites are used for communication, weather forecast, surveying and exploration of space.
77.
Mention the achievements of Indian space programme. India has made many achievements. a) Indian space scientists have successfully built many types of satellites. They include communication satellites, meteorological satellites, remote sensing satellites and scientific satellites. b) Many of these satellites have been launched from India itself using rockets like PSLV, GSLV. c) PSLV has been used to launch many satellites of other countries.
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d) India has successfully sent an unmanned spacecraft to explore the moon. e) ISRO launched a spacecraft to explore planet Mars. 78.
Expand the following. ISRO – Indian Space Research Organisation PSLV – Polar Satellite Launch Vehicle
79.
GSLV – Geosynchronous Satellite Launch Vehicle Name the following. a) The place from which the first indigenous sounding rocket was launched – Thumba b) India’s first artificial satellite – Aryabhata c) India’s first experimental remote sensing satellite – Bhaskara I d) First satellite to be launched from Indian soil – Rohini e) India’s first experimental communication satellite – APPLE f) India’s first operational remote sensing satellite – IRS 1A g) India’s first indigenously built multipurpose satellite – INSAT h) India’s first unmanned spacecraft to moon – Chandrayaan 1
Fill in the blanks: 1. The stage of star where a gaseous cloud of hydrogen is formed at the centre is protostar. 2. 3.
The raw material for the formation of protostar is hydrogen. Sun is in steady stage.
4.
The stage of the star where the outer envelope gets detached and thrown out into space is called planetary nebula.
5.
The value of Chandrashekar’s limit 1.4 times the mass of the sun.
6.
The heaviest element formed in the stellar evolution before supernova explosion is iron.
7.
The last stage in the stellar evolution of stars which are 5 times the mass of sun is supernova.
8.
The stage of star formed by the remnants of supernova is neutron star.
9. 10. 11.
A star which is composed of tightly packed neutrons is neutrons star. A spinning neutron star emitting radiowaves is called pulsar. The galaxies which are brighter than ordinary galaxies are called Quasars.
12.
The short from of ‘Quasi-stellar sources’ is Quasar.
13.
The end stage of a star whose mass is 30 times the mass of the sun is black hole.
14.
A small region having intense gravitational field is called black hole.
15. 16.
The properties that can be recognized in a black hole are density and gravity. If the radius of the sun is reduced to 3km it can become a black hole.
17. 18.
The name of our galaxy is Milky Way. Milky Way is an example of spiral galaxy.
19.
The unit used to measure stellar distances is light year.
20.
The diameter of Milky Way galaxy is one lakh light years.
21. 22.
The central thickness of Milky Way galaxy is 6000 light years. In the Milky Way galaxy, sun is located about 28,000 light years from the centre.
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23.
The matter in the universe was compressed into a very small fiery region called primordial fire ball.
24.
Big Bang Theory was proposed by Edwin Hubble.
25. 26.
The velocity of recession is proportional to its distance from us is Hubble’s Law. The mixture of oxidizer and fuel is called propellant.
27. 28.
An example of solid propellant is Polybutadiene and aluminium perchlorate. An example of liquid propellant is liquid hydrogen and liquid oxygen.
29.
Rocket propulsion is based on the principle of conservation of momentum.
30. 31.
The scientific instruments placed in the front portion of rocket is called payload. The product of rate of fuel consumption and exhaust velocity is called Thrust.
32.
The ratio of payload mass to the fuel mass is called payload ratio.
33.
The velocity of the body moving along a circular path is called orbital velocity.
34.
The formula for orbital velocity of a satellite at a height ‘h’ is Vo =
35.
Several rockets joined one on top of another is called multistage rocket.
36.
The minimum velocity with which a rocket must be projected to get away from earth’s gravitational field is called escape velocity.
37.
The value of escape velocity for earth is 11.2 kms .
38.
The relation between orbital velocity and escape velocity is Ve = 2 Vo .
39. 40. 41. 42.
The value of escape velocity is √𝟐 times the orbital velocity. Satellites which have an orbital period of 24 hours are called geostationary satellites. Geostationary satellites are also called communication satellites. The number of geostationary satellites required to cover every part of globe is three.
43. 44. 45.
A geostationary satellite must be placed at a height of 36,000km from the surface of the earth. The first Indian to fly into space is Rakesh Sharma. The unmanned spacecraft sent by India to explore the moon was Chandrayaan – 1.
46. 47.
The first Indian built rocket was launched from Thumba. The first Indian artificial satellite was Aryabhatta.
48.
The first Indian remote sensing satellite was Bhaskara 1.
49. 50.
India’s first experimental communication satellite was APPLE. India’s first indigenously built multipurpose satellite series is INSAT.
GM . R+h
-1
U
****
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226
A accommodation of the eye acid rain acromegaly ACTH Actinides adipose tissue adrenal glands adrenaline Aedes aegyptii aeroponics aestivation AIDS air pollution Algin aliphatic hydrocarbons alkanes alkenes alkynes allergens allotropy alloy alnico amines amino acids amorphous silicon amphibians amphoteric oxides amplitude angiosperms animal husbandry annealing of glass antheridia antioxidants aquaregia aqueous humour archegonia arenes areolar tissue armature aromatic hydrocarbons Arrhenius theory of dissociation arsenic artificial radioactivity aryl group asbestos astigmatism atomic size audible range Australoids
215 15 205 204 23 60 207 207 68 195 46 70 12 36 113 113 117 117 11 109 160 161 122 122 31 45 146 77 40 196 99 37 198 99 214 37 119 60 166 119 233 11 91 122 11 216 25 138 242
INDEX Australopithecus autonomic nervous system aves axon
239 213 47 64
B bagasse benzene Berzelius Bhopal gas tragedy bias voltage biasing bio diesel bio gasification biodegradable pollutants biogas bio-magnification biomass biotechnology birth hormone black hole blood plasma bloodless surgery bone marrow borax Boyle’s law brass breeder reactor bronze bryophytes
133 120 112 187 178 180 5 5 9 4 10 4 228 205 245 62 139 62 99 185 161 93 161 36
C calcination Capoids caramel carborundum carboxylic acids carburettor cardiac muscles carp cartilage tissue cataract catenation Caucasoids celotex cerebellum cerebro spinal fluid CFC chain reaction Chandrashekar’s limit charge Charles’s law chemotropism
155 242 131 32 121 89 59 44 61 216 110 241 133 211 209 14 91 244 156 184 202
RT I B
chikungunya chlorenchyma chordates chromatids ciliary muscles cloning collenchyma colourants combustion pyrolysis commutator companion cells concentration of ore Congoids conjunctiva control rods convolutions corpus callasum crank shaft cretinism Cro-Magnon cryolite crystalline silicon cuboidal epithelium cullets cuticle cycloalkanes
P24: Space Science 67 54 43 226 214 229 54 198 5 168 56 154 242 213 93 210 210 89 206 241 158 31 58 98 57 118
D D2 O dehydrating agent dendrites dengue fever diabetes incipidus diabetes mellitus diaphragm diencephalon diffusion dihybrid cross diode diphyodont DNA finger print technology DNA replication Dobereiner’s law of triads dominant trait dopants doping Doppler Effect drying agent Dryopithecus duralumin dwarfism dynamo rule Girish.N, Bengaluru
93 132 63 67 205 207 48 210 186 224 179 48 228 227 18 223 177 177 142 132 239 161 205 165
262
E echo echo Cardiograph echo-ranging effector Einstein’s mass energy relation electrolytic conduction electromagnetic induction electronic conduction electroplating electro-positive endolymph enrichment epidermal tissue epithelial tissue escape velocity eutrophication exocrine glands external fertilisation extrinsic semiconductor
137 141 140 209 92 232 164 232 235 26 217 92 56 57 251 12 203 45 177
F Faraday’s constant 235 Faraday’s first law 165 Faraday’s first law of electrolysis 234 Faraday’s second law of electrolysis 234 Faraday's second law 165 fermentation 5, 131 flavourants 198 Fleming's left hand rule 169 Fleming's right hand rule 165 flux 155 food additives 198 fractional crystallization 160 Friedrich Wohler 111
G gametophyte gangue gel electrophoresis gelidium genes genetics genital herpes genital warts genotype geostationary satellite geothermal energy geotropism gigantism glaucoma glazing of ceramics global warming 9844217032
37 154 229 36 226 222 69 69 224 252 7 202 205 217 102 14, 15
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glycerides gobar gas gonads gonorrhea Graham’s law of diffusion greenhouse effect greenhouse gases greenhouses growth hormone growth regulators gymnosperms
P24: Space Science 123 4 208 69 187 15 15 15 204 202 39
H Haversian system heavy water hepatitis B heredity heterodont heterogyous hibernation histology hole homeothermic animals Homo habilis Homo sapiens homologous series homozygous hormones Hubble’s law hybridization hydraulic washing hydrocarbons hydrogenation of oils hydroponics hydrosol hydrotropism hyper-metropia hyperthyroidism hypothalamus hypothyroidism
62 93 70 222 48 226 46 53 177 48 240 240 116 226 203 247 192 155 113 124 195 133 202 216 206 210 206
I in-breeding incomplete dominance incus induced current induced mutation induction coil inflorescence infrasonic inner transition elements insulin internal fertilization Girish.N, Bengaluru
197 225 217 164 193 173 40 138 24 207 46
intrinsic semiconductor Invar steel involuntary muscles ionisation energy irritability islets of Langerhans isomerism isotope IUPAC
263 177 161 59 26 202 207 110 21 114
J Jatropha Java man junction potential
6 240 178
K Kharif crops
191
L lacrymal glands laminaria land pollution Lane process lanthanides ligaments livestock longitudinal waves lymph
213 36 13 149 23 61 197 75 63
M malleus mammalia marsh gas mechanical waves medulla oblongata megasporophyll memory alloys Mendel’s law of Independent Assortment Mendel’s law of segregation Mendel’s principle of dominance Mendeleev’s periodic law meninges meristematic tissues metallic nature metalloids metallurgy metamorphosis metaphyta (plantae) microsporophyll moderator modern periodic law molasses Mongoloids 9844217032
217 48 113 75 211 39 162 225 225 223 20 209 53 27 27 154 45 35 39 93 21 133 241
RT I B
monohybrid cross mordant motor rule multi-cellular algae mutagens mutants mutations mutual induction Myelin sheath myopia
P24: Space Science 222 158 169 35 193 193 14, 228 170 64 216
N naphthalene Neanderthal man neuron neutron star Newland’s law of Octaves nickel steel noble gases noise pollution non-biodegradable non-renewable norit nuclear fission nuclear fusion
120 240 63 245 20 161 22 14 9 2 133 91 95
O octet structure olfactory epithelium orbital velocity ore organ of corti organic chemistry oscillation oscillator out-crossing oviparous animals oxidizer
22 218 250 154 217 112 77 182 197 45 247
P paraffins parathormone parenchyma payload ratio Peking man pentadactyl perilymph periodicity permanent tissues personality hormone phagocytes phenotype phototropism Girish.N, Bengaluru
113 206 54 248 240 46 217 25 54 205 63 224 202
264
phycoerythrin 35 phytohormones 202 pisces 44 pituitary gland 204 placenta 49 planetary nebula 244 plant hormones 202 p-n junction 178 pneumatic bones 47 poikilothermic animals 45 pollutants 9 pollution 9 poly-functional compounds 122 polyploidy 193 pons 211 porphyra 36 presbyopia 216 primates 239 principle of conservation of momentum 248 progesterone 208 propellant 247 prothallus 38 protostar 244 pteridophytes 37 PUFA 126 pulping of paper 104 pulsar 245 pure semiconductor 177 purines and pyramidines 227
Q quasars
245
R rabi crops RADAR radar gun radioactive pollution Ramapithecus rancidity receptor recessive trait recombinant DNA technology rectifier red shift reflex action reflex arc reptiles reticular tissue retro virus reverse transcriptase rhizoids
191 143 143 16 239 124 209 223 194, 228 179 142 212 212 46 60 70 71 36
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roasting roof-top gardening
P24: Space Science 154 196
S sacculus salicylic acid saponification sclereids sclerenchyma semiconductors sieve plate sieve tubes silicon carbide silicones silicosis simple goitre simple harmonic motion simple permanent tissue slag solar cell solar collector solar constant solar energy solar pond SONAR spark plug sporophytes squamous epithelium stapes stearic acid stomata striped muscles substitution reaction sucrose superconductors supernova syphilis
217 123 125 55 55 176 56 56 32 33 33 206 77 54 155 4 3 3 3 3 139 89 37 57 217 124 57 58 116 131 182 245 69
T tendons testis thalamus thallus thecodont thermal pollution thermotropism thigmotropism thyroxin
Girish.N, Bengaluru
61 208 210 35 48 13 202 202 205
time period tissue culture toluene totipotency tracheids tracheophytes trans esterification transformer transgenic animals transgenic plants transistor transition elements transmutation transverse waves tropism TSH
265 77 193 120 194 56 37 6 170 198 194 180 24 91 75 202 204
U ultra pure metal ultrasonic sounds unstriped muscles utriculus
159 138 58 217
V vascular plants vector DNA vital force theory vitrectomy vitreous humour viviparous animals Volkmann’s Canal voluntary
35 194 111 216 214 48 62 59
W water pollution wave velocity wavelength wind energy wind turbine wort
12 74 75 6 6 134
X xanthophyll
35
Z zero group elements Zinjanthropus zone refining
22 239 160
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