UPSC Combined Geo-Scientist
Chemist
- 3 descriptive papers
- 200 marks each
- 3 h per paper
Mains Paper II covers physical chemistry.
All years
Pages 1 and 2 of 33 
Pages 3 and 4 of 33 
Pages 5 and 6 of 33 
Pages 7 and 8 of 33 
Pages 9 and 10 of 33 
Pages 11 and 12 of 33 
Pages 13 and 14 of 33 
Pages 15 and 16 of 33 
Pages 17 and 18 of 33
Pages 19 and 20 of 33 Pages 21 and 22 of 33 Pages 23 and 24 of 33 Pages 25 and 26 of 33 Pages 27 and 28 of 33 Pages 29 and 30 of 33 Pages 31 and 32 of 33 Page 33 of 33 
Mains Paper II, physical chemistry
Solution, 2025
UPSC Combined Geo-Scientist, Stage II (Mains). 33 pages. Questions 1, 2, 4, 5, 6, 7, 10, 11, 12 and 13 are answered.
Every question of 2025, one page each36 parts in 15 questions, with the question as text and the key points of its answer
Question 1 80 marks
- 1(a)Why Z > 1 for H₂ and He at all pressures5 marks
- 1(b)Corresponding state of H₂S for N₂ at 25 °C and 1 atm5 marks
- 1(c)Band structure of n-type and p-type semiconductors5 marks
- 1(d)Symmetry elements of orthorhombic Mg₂SiO₄5 marks
- 1(e)Fall of G with temperature at constant pressure5 marks
- 1(f)Z > 1 and f > P for the gas P(Vm − b) = RT5 marks
- 1(g)Overall equation and the role of each species5 marks
- 1(h)log k against pH for specific H⁺ catalysis5 marks
- 1(i)KCl salt bridge for a silver–lead cell5 marks
- 1(j)Equilibrium constant from standard potentials5 marks
- 1(k)Conditions for an acceptable wave function5 marks
- 1(l)No solution with E = 0 for the particle in a box5 marks
- 1(m)Discrete levels and the resonance condition5 marks
- 1(n)Rotational activity of CO and CO₂5 marks
- 1(o)Measuring light intensity with a chemical actinometer5 marks
- 1(p)Why watch hands glow in the dark5 marks
Question 2 10 marks
Question 3 10 marks
Question 4 10 marks
Question 5 10 marks
Question 6 10 marks
Question 7 10 marks
Question 8 10 marks
Question 9 10 marks
Question 10 10 marks
Question 11 20 marks
Question 12 20 marks
Question 13 20 marks
Question 14 20 marks
Part of VKC Basic
Read the full model answer to every question of this paper with VKC Basic
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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 Combined Geo-Scientist (Main) Chemistry Paper II: Model Answers 2021 to 2025
The book has all five years of Paper II in one volume, with all fifteen 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.