UPSC Civil Services (Mains)
Chemistry optional
- 2 papers
- 250 marks each
- 3 h per paper
- 5 of 8 questions, Q1 and Q5 compulsory
Paper II covers organic chemistry and spectroscopy.
All years
Pages 1 and 2 of 22 
Pages 3 and 4 of 22 
Pages 5 and 6 of 22
Pages 7 and 8 of 22 Pages 9 and 10 of 22 Pages 11 and 12 of 22 Pages 13 and 14 of 22 Pages 15 and 16 of 22 Pages 17 and 18 of 22 Pages 19 and 20 of 22 Pages 21 and 22 of 22 
Paper II, organic chemistry and spectroscopy
Solution, 2025
UPSC Civil Services (Mains), Chemistry optional. 22 pages. Questions 1, 3, 5, 6 and 8 are answered.
Every question of 2025, one page each48 parts in 8 questions, with the question as text and the key points of its answer
Question 1 50 marks
Question 2 50 marks
Question 3 50 marks
- 3(a)(i)Products of two reactions10 marks
- 3(a)(ii)Ketone A from isobutanol alone5 marks
- 3(b)(i)Cyclopropane from tert-butyl chloroacetate and ethyl acrylate10 marks
- 3(b)(ii)Structures of C and D5 marks
- 3(c)(i)Missing reagents and intermediate10 marks
- 3(c)(ii)Photolysis of the α-diazoketone in methanol10 marks
Question 4 50 marks
- 4(a)(i)Molecular weight of poly(p-hydroxybenzoic acid)7 marks
- 4(a)(ii)Structure of the polymer3 marks
- 4(a)(iii)Precursor of natural rubber5 marks
- 4(b)(i)Nylon 6 and nylon 6,6 compared5 marks
- 4(b)(ii)Preparing syndiotactic polystyrene5 marks
- 4(b)(iii)Salient features of the α-helix5 marks
- 4(c)(i)Two dichlorides with NaN₃: neighbouring sulfur10 marks
- 4(c)(ii)Kinetic and thermodynamic enolates trapped with D₂O10 marks
Question 5 50 marks
Question 6 50 marks
- 6(a)(i)Products and intermediates of two reductions10 marks
- 6(a)(ii)Role of NMO in catalytic dihydroxylation5 marks
- 6(b)Three numericals15 marks
- 6(c)(i)Benzene to fulvene by light5 marks
- 6(c)(ii)Quantum yield of photobromination5 marks
- 6(c)(iii)Photolysis of 4,5-dimethylhexan-2-one5 marks
- 6(c)(iv)A, B and C from the mixed ketones5 marks
Question 7 50 marks
- 7(a)(i)Two UV bands of acetone5 marks
- 7(a)(ii)λmax by the Woodward–Fieser rules10 marks
- 7(b)(i)Diels–Alder reactivity of four dienes10 marks
- 7(b)(ii)2-Methoxybutadiene with acrylonitrile5 marks
- 7(c)(i)Rearrangement of a cis-divinylcyclopropane10 marks
- 7(c)(ii)Mode of ring closure in two electrocyclic reactions10 marks
Question 8 50 marks
- 8(a)(i)Coupling constants of the lettered protons5 marks
- 8(a)(ii)Chemical shifts of Hᵃ and Hᵇ5 marks
- 8(a)(iii)Number of ¹H NMR signals5 marks
- 8(b)(i)Structure of the halogenated ester10 marks
- 8(b)(ii)C₆H₁₂ alkenes with peaks at m/z 42 and 565 marks
- 8(c)(i)Characteristic fragment ions10 marks
- 8(c)(ii)Structure of C₄H₅NO₂10 marks
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Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Model answer pages open with the VKC plan.
Printed copy and Kindle
UPSC Civil Services (Main) Chemistry Paper II: Model Answers 2021 to 2025
The book has all five years of Paper II in one volume, with every question printed above its answer, mechanisms labelled on the scheme, the topic-wise weightage of marks and a topic-wise index.