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
Pages 1 and 2 of 40 
Pages 3 and 4 of 40 
Pages 5 and 6 of 40 
Pages 7 and 8 of 40 
Pages 9 and 10 of 40
Pages 11 and 12 of 40 Pages 13 and 14 of 40 Pages 15 and 16 of 40 Pages 17 and 18 of 40 Pages 19 and 20 of 40 Pages 21 and 22 of 40 Pages 23 and 24 of 40 Pages 25 and 26 of 40 Pages 27 and 28 of 40 Pages 29 and 30 of 40 Pages 31 and 32 of 40 Pages 33 and 34 of 40 Pages 35 and 36 of 40 Pages 37 and 38 of 40 Pages 39 and 40 of 40 
Mains Paper III, analytical and organic chemistry
Solution, 2023
UPSC Combined Geo-Scientist, Stage II (Mains). 40 pages. Questions 1, 4, 5, 6, 7 and 10 are answered.
Every question of 2023, one page each48 parts in 10 questions, with the question as text and the key points of its answer
Question 1 40 marks
- 1(a)Relative standard deviation of replicate results5 marks
- 1(b)HPLC against GLC; particle size of packed GLC columns5 marks
- 1(c)Sources of radiation for infrared spectrometry5 marks
- 1(d)Graphite-furnace AAS compared with flame AAS5 marks
- 1(e)Calibration of the temperature axis in thermogravimetry5 marks
- 1(f)K and L lines in XRF; wavelength-dispersive spectrum of Zn5 marks
- 1(g)Interference of calcium in the ICP–MS determination of iron5 marks
- 1(h)Type metal: constituents and non-destructive analysis5 marks
Question 2 30 marks
Question 3 30 marks
Question 4 30 marks
Question 5 30 marks
Question 6 40 marks
- 6(a)Chlorocarbene from CH₂Cl₂; ring expansion of 3-methylindole4 marks
- 6(b)Ozonolysis of camphene, then Wolff–Kishner reduction4 marks
- 6(c)Reductive amination, then intramolecular aza-Michael addition4 marks
- 6(d)Benzaldehyde and ethane-1,2-dithiol: a 1,3-dithiolane4 marks
- 6(e)Amidomercuration–demercuration of hex-1-ene in acetonitrile4 marks
- 6(f)Dimerisation of cyclopentadiene: endo rule by frontier orbitals4 marks
- 6(g)Two isomeric esters C₇H₁₄O₂ from ¹H NMR4 marks
- 6(h)Mass spectrum of 3-butyn-2-ol: the ion of m/z 554 marks
- 6(i)Acetone: solvent shift of the n → π* band4 marks
- 6(j)Butyrophenone: McLafferty rearrangement and α-cleavage4 marks
Question 7 30 marks
Question 8 30 marks
Question 9 30 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.
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 Combined Geo-Scientist (Main) Chemistry Paper III: Model Answers 2021 to 2025
The book has all five years of Paper III in one volume, with all ten questions of every paper answered, the question printed above each answer, a time plan for each paper, the topic-wise weightage of marks and a topic-wise index.