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CSS Chemistry Paper II Past Paper 2025

CSS Chemistry Paper II 2025 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.

  1. Q. 2
    • (a)
      Elaborate with examples that how resonance, hyperconjugation and inductive effect, can contribute towards the stability of carbocations.
      (10)
    • (a)
      How ‘dipole moment’ can be measured? Indicate, among the following molecules which does not have dipole moment and why?
      (10)
      • (i)
        CClX4\ce{CCl4}
      • (ii)
        BFX3\ce{BF3}
      • (iii)
        CHX4\ce{CH4}
      • (iv)
        NHX3\ce{NH3}
  2. Q. 3
    • (a)
      How does the reaction mechanism work for the electrophilic addition of bromine to ethene? Explain the intermediate (s).
      (10)
    • (b)
      Describe the IUPAC rules for naming alkenes and alkynes with appropriate examples.
      (10)
  3. Q. 4
    • (a)
      Categorize benzene substituents, into activating and deactivating groups. Explain their influence on ortho, para and meta orientation of incoming groups in electrophilic substitution reactions.
      (12)
    • (b)
      How did Kekulé propose the benzene structure, and what evidence supported his model?
      (8)
  4. Q. 5
    • (a)
      Compare the reactivity of acid halides, anhydrides, esters, and amides toward nucleophilic substitution. What kind of products do you expect when these react with Grignard reagent (RMgX)?
      (10)
    • (b)
      Explain the reaction mechanism of Williamson synthesis to prepare ethers.
      (5)
    • (c)
      Discuss the acidic nature of phenols. Why picric acid (CX6HX3NX3OX7\ce{C6H3N3O7}) is considered strong acid?
      (5)
  5. Q. 6
    • (a)
      Given below is the structure of (1R, 2S, 5R) menthol. Draw the structures of all possible stereoisomers of menthol.
      (8)
      Skeletal structure of menthol: a cyclohexane ring with a methyl on a wedge at the top, OH on a wedge at the right, and an isopropyl group on a hashed bond at the bottom.
    • (b)
      How does Hofmann’s rule differ from Zaitsev’s rule? Explain each with suitable example.
      (6)
    • (c)
      Describe the main components of a UV/Visible spectrophotometer and their functions.
      (6)
  6. Q. 7
    • (a)
      Write a comprehensive note on primary, secondary, tertiary, and quaternary structures of proteins.
      (10)
    • (b)
      Write a note on enzyme catalysis and enzyme inhibition.
      (10)
  7. Q. 8
    • (a)
      Outline the steps of the Krebs cycle, and explain its role in cellular respiration.
    • (b)
      Describe the environmental impact of the manufacturing industry of sugar, cement, glass, paper and fertilizers. How these industries can address environmental concerns?
  1. Part-II is to be attempted on the separate Answer Book.
  2. Attempt ONLY FOUR questions from PART-II. ALL questions carry EQUAL marks.
  3. All the parts (if any) of each Question must be attempted at one place instead of at different places.
  4. Write Q. No. in the Answer Book in accordance with Q. No. in the Q.Paper.
  5. No Page/Space be left blank between the answers. All the blank pages of Answer Book must be crossed.
  6. Extra attempt of any question or any part of the question will not be considered.
  7. Use of Calculator is allowed.