Organic Chemistry-Chemistry-BSC-Nagpur-Summer-2019

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 hybridisation ? Explain the structure of Ethylene molecule on the basis of hybridisation. [5M]

(B) Discuss Homolytic and Heterolytic fission of covalent bond with suitable example. [5M]

OR

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

(D) Discuss hydrogen bonding with reference to alcohol. [2½M]

(E) Define the terms with suitable example :

(i) Substitution reaction and

(ii) Elimination reaction. [2½M]

(F) Classify the following as electrophiles and nucleophiles :

(i) FeCl₃ (ii) H₂O (iii) CH₃NH₂ (iv) BF₃ and (v) AlCl₃. [2½M]

2. (A) What is Optical activity ? Discuss optical isomerism in Tartaric acid and Lactic acid. [5M]

(B) Define conformation. Discuss conformational isomerism of n-butane. [5M]

OR

(C) Explain geometrical isomerism in Maleic and Fumaric acid. [2½M]

(D) Write a note on Newman’s projection and Sawhorse formulae of Ethane. [2½M]

(E) Discuss D and L nomenclature with suitable example. [2½M]

(F) What is Resolution ? Explain biological method of resolution [2½M]

3. (A) What is Peroxide effect ? Explain free radical mechanism of addition of HBr to propene. [5M]

(B) Discuss Baeyer’s strain theory. Give its limitations. [5M]

OR

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

(D) Write a note on L.P.G. [2½M]

(E) How will you prepare ethylene from :

(i) Ethyl alcohol and

(ii) Ethyl bromide ? [2½M]

(F) Discuss Ionic mechanism of addition Br2 to ethylene. [2½M]

4. (A) What are dienes ? How they are 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) Explain acidic nature of ethyne. [2½M]

(D) Discuss the Diels—Alder reaction. [2½M]

(E) Discuss molecular orbital structure of Benzene. [2½M]

(F) What is Huckel rule ? Explain aromaticity of cyclopentadienyl anion. [2½M]

5. Solve any TEN of the following :—

(i) Define Carbonium ion.

(ii) Draw M.O. Structure of Ethane molecule.

(iii) Give one example of addition reaction.

(iv) What is Asymmetric synthesis ?

(v) What is meant by stereogenic centre ?

(vi) What is racemisation ?

(vii) Draw structure and give IUPAC name of neopentane.

(viii) What is the action of O₃ on Ethylene ?

(ix) Define Octane number.

(x) What is oxyacetylene flame ?

(xi) Give the polymerisation reaction of acetylene.

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