Organic Chemistry-Chemistry-BSC-Nagpur-Summer-2017

Bachelor of Science (B.Sc.) Semester—2 Examination
CHEMISTRY (Organic Chemistry)

Optional Paper—1
Time : 3 Hours
Maximum Marks : 50

N.B. :— (1) All questions are compulsory and carry equal marks.
(2) Draw well labelled diagram wherever necessary.

1. (A) What is hybridization ? Explain the structure of ethane on the basis of hybridization. [5M]

(B) What are Reactive intermediates ? Explain the formation and stability of carbocations. [5M]

OR

(C) Write a note on Inductive effect. [2½M]

(D) Define free radicals. Discuss the stability of free radicals. [2½M]

(E) Define the terms :

(i) Bond length and

(ii) Bond angle. [2½M]

(F) Discuss with example Homolytic bond fission. [2½M]

2. (A) What is Resolution ? Describe various methods used for resolving racemic mixture. [5M]

(B) What is conformation ? Discuss the conformations of ethane. [5M]

OR

(C) Discuss the optical isomerism in Lactic acid. [2½M]

(D) Write a note on geometrical isomerism in 2-Butene. [2½M]

(E) State the sequence rules for assignment of RS-configuration. [2½M]

(F) Write a note on ‘Asymmetric synthesis.’ [2½M]

3. (A) Discuss Baeyer’s strain theory. What are the limitations of this theory ? [5M]

(B) What is Markownikoff’s rule ? Explain the ionic mechanism of addition of HBr to propene. [5M]

OR

(C) Discuss the mechanism of chlorination of methane. [2½M]

(D) How does ethene react with :

(i) Ozone and

(ii) Cold aqueous KMnO₄ ? [2½M]

(E) Write a note on L.P.G. [2½M]

(F) Give the preparation of propene from :

(i) 1–Propanol and

(ii) 2–Bromopropane. [2½M]

4. (A) What are Alkadienes ? How are they classified ? What is the action of :

(i) Bromine and

(ii) HBr on 1, 3–butadiene ? [5M]

(B) What is aromatic electrophilic substitution reaction ? Discuss mechanism of nitration of
benzene with energy profile diagram. [5M]

OR

(C) Describe Diel’s Alder reaction. [2½M]

(D) Discuss molecular orbiral structure of Benzene. [2½M]

(E) Write a note on acidic nature of acetylene. [2½M]

(F) Discuss the structure of benzene on the basis of resonance. [2½M]

5. Attempt any TEN of the following :

(i) What is Hydrogen bonding ?

(ii) Define the term nucleophile.

(iii) Draw molecular orbital diagram of ethylene molecule.

(iv) Define the term enantiomers.

(v) Write R-or-S configuration for the following :
CHO
H C OH
COOH

(vi) Draw Newman’s projection formulae of n-Butane.

(vii) State Saytzeff’s rule

(viii)What is peroxide effect ?

(ix) Define Octane number.

(x) Give polymerisation reaction of Acetylene.

(xi) What is the action of Bromine on 1, 3-Butadiene ?

(xii) State Huckel’s rule of aromaticity.         [10M]