Q1/7G/11-12 Reg. No

St. Joseph’s College of Arts & Science (Autonomous) St. Joseph’s College Road, Cuddalore – 607001 CH101S – ORGANIC CHEMISTRY - I Time : 3 hrs Max Marks :75 SECTION – A (20X1=20) Answer ALL Questions I. Choose the correct answer: 1. The shape of acetylene is ---------a) Square planar b) Tetrahedral

c) Planar

2. The IUPAC name of a) 3-hexene b) 4-hexene

is c) 3-hexyne

d) Linear

d) 4-hexyne

3. Homolysis of a covalent bond in a molecule results in the formation of a) Cation b) Anion c) Free radical d) Neutral molecules 4. Wurtz reaction is used to synthesis a) Alkynes b) Alcohols 5. No bond resonance exists in a) Ethylene b) Acetylene

c) Alkanes

c) Propene

d) Alkenes

d) Benzene

6. The most acidic compound among the following is a) Alkane b)Terminal Alkene c) Terminal Alkyne d) Cycloalkane 7. The molecule with the highest angular strain is a) Cyclohexane b) Cyclopentane c) Cyclobutane d) Cyclopropane

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Q1/7G/11-12 8. Which of the following molecules is the most stable? a) Ethylene b) Propene c) cis – 2-butene d) trans – 2 – butane 9. Thermodynamically controlled addition of hydrogen bromide to a conjucated diene is a) 1,2-addition b)1,3-addition c)1,4-addition d) 1,1-addition 10. Cumulative double bonds are present in a) Allenes b) Aromatic rings c) Alkyl halides

d) Alkynes

II. Fill up the blanks: 11. Bond angle in Methane is ----------. 12. Hydrogenation of an alkene results in the formation of ---------. 13. The amount of energy consumed when a bond is broken or liberated when formed is called ------. 14. Ozonolysis with reductive work up of propene results in the formation of-------- and ---------. 15. Hydrolysis of CH 3 MgBr gives -----------. III. Match the following: 16. 1,2- Diaxial

-

Alkane

17. Wurtz reaction

-

Hofmann

18. Elimination

-

Terminal alkynes

19. Acetylides

-

Conformation

20. Eclipsed

-

Trans

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Q1/7G/11-12 SECTION – B (10X2=20) Answer any TEN Questions 21. Arrange the following carbocations in the increasing order of their stability.

+

+

+

CH3

CH3CH2

,

,

CH3CHCH3

22. Write the product of the following reaction. H3C

C

C

CH3

+

H2

? Pd / CaCO

3

23. Give any two examples for geometrical isomers. 24. Define inductive effect and explain it with an example. 25. How is methane synthesized by Kolbe’s reaction? Give the reaction. 26. Predict the product for the following reaction. COOEt

C2H5ONa

COOEt

+

27.

Br2

?

28. How will you effect the following conversion? H3C

CH

CH3CHCH3

CH2

Cl

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Q1/7G/11-12 29. How will you do the following conversion? H3C H C C H3C C

C

CH2 CH3

30. Predict all the possible products of the following reaction. OH H3C

CH

CH

H2SO4

CH3

?

CH3

31. Draw the eclipsed and staggered conformations of ethane. 32. Predict the products A and B. O3 CH H2C 2 CH2Cl2

A

Zn / H2O

B

.

SECTION - C (5X7=35) Answer any FIVE Questions 33. a) Explan the hybridization involved in the formation of Acetylene.

(3)

b) How will you prepare Methane from Grignard reagent? Write the reaction. (4) 34. a) How will you prepare Acetaldehyde from 2- butene ? b) How will you effect the following conversion? Ethylene Ethyl Bromide

(4) (3)

35. a) Predict the products A and B of the following reactions and give the reason for their formation. (4)

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Q1/7G/11-12

+ K

t - BuO A

Cl H3C

CH2

CH

CH3 NaOEt B

b) Predict the product and give a suitable mechanism. H3C CH3 KMnO4 C C H NaOH H

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36. a) Give the reason for the acidic nature of Acetylene.

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b) How will you do the following conversion? H3C H3C

C

C

CH3

(3) CH3 C

C

H

37. a) Explain the acidic nature of Phenol based on resonance.

H

(4)

b) Compare the basic strengths of the following molecules and arrange them in the increasing order of their basic strengths. (3) Aniline, Ammonia and Methylamine 38. a) Write the structures of the following molecules. i) trans – 1,2 – dimethyl cyclohexane ii) trans – 1,4 - dimethyl cyclohexane iii) trans – 1,3 - dimethyl cyclohexane iv) cis – 1,3 - dimethyl cyclohexane

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(4)

Q1/7G/11-12 b) How will you prepare Butane by Wurtz reaction? 39. a)

Write the conformational changes of ethane when one of the two carbon atom is rotated about the C – C. (4)

b) Write the IUPAC Names of the following molecules. i)

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ii)

iii)

***********

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