CSS past paper

CSS Chemistry Paper II Past Paper 2020

CSS Chemistry Paper II 2020 carries 100 marks over 3 hours. It has 7 questions.

Marks: 100
Time: 3 hours
Questions: 7

Years

How to attempt: Attempt ONLY FOUR questions from PART-II. ALL questions carry EQUAL marks.

Questions

Question 1 (Part I) is the paper's MCQs, which are not reproduced here.

Q. 2
Explain the difference between: (5 each)
(20)
- (i)
  Inductive and Field effects
- (ii)
  Inductive and Resonance effects
- (iii)
  Localized and Delocalized bonding
- (iv)
  Conjugation and Hyperconjugation
Q. 3
(20)
- (a)
  “ The resonance effect has an appreciable influence on physical characteristics and the chemical reactivity of organic molecules”. Elaborate the statement with the help of examples.
  (10)
- (b)
  Outline the EAS mechanism (Electrophilic Aromatic Substitution) through which aromatic compounds react with electrophiles.
  (5)
- (c)
  Discuss factors which favour an elimination reaction occurring over a substitution reaction.
  (5)
Q. 4
How would you carry out the following conversions? Account for your answer with mechanism in each case. (4 each)
(20)
- (i)
  $\ce{(CH3)3CCH=CH2 -> (CH3)2C(OH)CH(CH3)2}$
- (ii)
  $\ce{(CH3)3CCH=CH2 -> (CH3)3CCH(OH)CH3}$
- (iii)
  $\ce{(CH3)3CCH=CH2 -> (CH3)3CCH2CH2OH}$
- (iv)
  $\ce{(CH3)3CC#CH -> (CH3)3CCOCH3}$
- (v)
  $\ce{(CH3)3CC#CH -> (CH3)3CCH2CHO}$
Q. 5
The following reactions can be used for the preparation of alkanes or cycloalkanes. Elaborate them with the help of reaction mechanisms. (5 each)
(20)
- (i)
  Corey House reaction
- (ii)
  Wurtz reaction
- (iii)
  Kolbe reaction
- (iv)
  Simmons - Smith Reaction
Q. 6
How would you convert cyclohexanone into the following compounds? Write down the mechanisms of the reactions. (4 each)
(20)
- (a)
  Caprolactone
- (b)
  Caprolactam
- (C)
  Cycloheptanone
- (d)
  Cyclohexa-1,2-dione
- (f)
  Cyclohexane
Q. 7
(20)
- (a)
  How can a racemic mixture be separated into its components? Describe different methods.
  (16)
- (b)
  (-)-Lactic acid has a specific rotation of – 3.8°. What will be the specific rotation of a solution containing 7.5g of (-)-lactic acid and 2.5 g of (+)-lactic acid?
  (4)
Q. 8
(20)
- (a)
  Starch, glycogen and cellulose are polymers of glucose. How will you differentiate among these three both structurally and functionally.
  (12)
- (b)
  Explain precisely the following terms.
  (8)
  - (i)
    Glycolysis
  - (ii)
    Glycogenolysis
  - (iii)
    Glycogenesis
  - (iv)
    gluconeogenesis

Part-II is to be attempted on the separate Answer Book.
Attempt ONLY FOUR questions from PART-II. ALL questions carry EQUAL marks.
All the parts (if any) of each Question must be attempted at one place instead of at different places.
Candidate must write Q. No. in the Answer Book in accordance with Q. No. in the Q.Paper.
No Page/Space be left blank between the answers. All the blank pages of Answer Book must be crossed.
Extra attempt of any question or any part of the attempted question will not be considered.