Download "Organic Chemistry-A Paper-2" Previous Years Question Paper of B.Sc. (General) for 1st Semester.

B.Sc. (General) 1st Semester

Chemistry(Same for B.Sc. Microbial & Food Tech.)

Paper-II: Organic Chemistry-A

Time Allowed: Three Hours] [Maximum Marks: 22 

Note:- Attempt five questions in all selecting one from each Unit. Q.No. 9 is compulsory.

UNIT-I 

1. (a) Define resonance effect. Explain why allyl and benzyl halides are more reactive than primary alkyl halides towards nucleophilic substitution reaction? 

(b) What conditions are to be satisfied for a compound to be aromatic? State which of the following are aromatic and why?

 

2. (a) What are substitution reactions ? Give one example each for nucleophilic, electrophilic, and free radical reactions. 

(b) Give details for the various methods available for determining the reaction mechanism of a reaction. 2,2

    

UNIT-II 

3. (a) Give the details for the preparation of alkanes via decarboxylation of carboxylic acids. 

(b) Write a note on nitration of alkanes.  2,2 

4. (a) Write a note on [2 + 2] cycloaddition reactions for the preparation of cycloalkanes. 

(b) Discuss the salient features of Baeyer's strain theory. Calculate the angle strain in cyclobutane.  2,2

UNIT-III 

5. (a) What is metamerism ? Give a suitable example.

(b) Define the term, specific rotation. 

(c) Write a note on the inversion, retention of configuration, and racemization. 1,1,2 

6. (a) Giving suitable examples, differentiate between chiral centers and chiral molecules. 

(b) Draw the various possible stereoisomers for 2, 3-dichloro pentane. 

(c) Assign R or S configuration to the different chiral centers in the following compounds, showing the proper priority according to the CIP rule : 

 

UNIT-IV 

7. (a) With the help of the Newmann projection formula, explain why the chair form of methylcyclohexane is more stable as compared to the boat form? 

(b) What is the necessary and sufficient condition for geometrical isomerism in oximes?    2,2

8. (a) Write a detailed note on the determination of the configuration of geometrical isomers on the basis of their physical properties. 

(b) Assign E or Z nomenclature to the following compounds, showing the proper priority according to the CIP rule :

 

COMPULSORY QUESTION 

(a) Differentiate between localized and de-localized bonds. 

(b) What are nitrenes? Differentiate between singlet and triplet nitrenes. 

(c) Give the IUPAC nomenclature for the following compounds :

(d) Draw the Sawhorse, Fischer, Newmann, and Flying-Wedge projection for lactic acid. 

(e) How does geometrical isomerism affect melting point and boiling points? 

(f) Discuss the various methods for the resolution of a racemic mixture. 1x6