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KSHATRIYA VIDHYASALA MATRIC HR. SEC. SCHOOL, THOOTHUKUDI- 628002. STD XII

UNIT TEST-III (SOLID STATE)

SUBJECT: CHEMISTRY

MAX. MARKS: 50 DURATION: 90mins

Instructions: 1. Use Black or Blue ink to write and pencil to draw diagrams. 2. Draw diagrams wherever necessary. Part-I CHOOSE AND WRITE THE CORRECT ANSWERS:

(9 X 1 = 9)

1. The number of close neighbours in a body centered cubic lattice of identical spheres is a) 6 b) 4 c) 12 d) 8 2. Semiconductors which exhibit conductivity due to the flow of excess negative electrons are called: a) Super conductors c) n- type semicondutors b) P- type semiconductors d) Insulators. 3. Which of the following is molecular crystal? a) Noble gas b) Ice c) 1 and 2 both c) None 4. Diamond is an example of a) Solid withhydrogen bonding c) Electrovalent bond b) Covalent bond d)Glass 5. Glass is…….. a) Supercooledliquid c) Crystalline solid b) Amorphous Solid d) Both (a) and (c) 6. Structure of ZnS is a) Body Centered Cubic c) Face Centered Cubic b) Simple Cube d) Flourite structure 7. In a face centered cubic lattice, a unit cell is shared equally by how many unit cells…… a) 8 b) 4 c) 2 d) 6 8. Body centered cubic lattice has a coordination number of a) 4 b) 8 c) 12 d) 6 9. In the crystal of CsCl, the nearest neighbours of each Cs ion are………. a) Six chloride ions c) eight chloride ions b) Six Cs ion d) eight Cs ion

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Part- B Note : ( 7 X 3 = 21) 1. Answer any seven questions 2. Each answers should be in two or three sentences 1. 2. 3. 4. 5. 6. 7. 8. 9.

How are glasses formed? What is a vitreous state? What are Super Conductors? What is molecular crystal? Give an example Sketch the following lattices a) Simple Cubic b) Body Centered Cubic Give the uses of Super Conductors. State Braggs law. What is Super Conducting Transition temperature? Calculate the number of CsCl unit in crystal.

c) Face Centered Cubic

Part- C Note: (i)

1. 2. 3. 4. 5.

(4 X 5 = 20) Ques. No: 5is compulsory and Answer any three questionsfrom the remaining questions.

Explain Schottky and Frenkel defect. Write the properties of ionic crystals. Explain the nature of glasses. Explain Braggs’ Spectrometer method in the study of crystals. Find the interplanar distance in a crystal in which series of planes produce a first order reflection from a copper X-ray tube ( λ = 1.542 Aº) at an angle of 23.2º.

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