UPSC Combined Geo-Scientist
Chemist
- 3 descriptive papers
- 200 marks each
- 3 h per paper
Mains Paper III covers analytical and organic chemistry.
All years
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Mains Paper III, analytical and organic chemistry
Solution, 2026
UPSC Combined Geo-Scientist, Stage II (Mains). 30 pages. Questions 1, 3, 4, 6, 8 and 10 are answered.
Every question of 2026, one page each43 parts in 10 questions, with the question as text and the key points of its answer
Question 1 40 marks
- 1(a)Classification of samples by size5 marks
- 1(b)Stationary-phase film thickness in gas chromatography5 marks
- 1(c)Percentage of amine from the absorbance of its picrate5 marks
- 1(d)Principle of vapour-generation AAS5 marks
- 1(e)Purge gases in thermogravimetric analysis5 marks
- 1(f)X-ray fluorescence in X-ray diffraction5 marks
- 1(g)Argon in ICP-MS; acids for arsenic5 marks
- 1(h)MnO₂ in pyrolusite by back titration5 marks
Question 2 30 marks
Question 3 30 marks
Question 4 30 marks
Question 5 30 marks
Question 6 40 marks
- 6(a)Hofmann and Schmidt reactions4 marks
- 6(b)Cannizzaro; LiAlH₄ on a lactam; selective reduction of an ester4 marks
- 6(c)Gramine from indole and its displacement by cyanide4 marks
- 6(d)Benzoin condensation and Darzens reaction4 marks
- 6(e)Two epoxidations of carvone4 marks
- 6(f)Photochemistry of stilbene4 marks
- 6(g)Racemisation of an optically active 1,5-diene4 marks
- 6(h)Identify the amide from its IR bands4 marks
- 6(i)Woodward–Fieser rules for three dienes4 marks
- 6(j)Halogens from the M, M+2 and M+4 peaks4 marks
Question 7 30 marks
Question 8 30 marks
Question 9 30 marks