Indian Forest Service (Mains)
Chemistry optional
- 2 papers
- 200 marks each
- 3 h per paper
Paper I covers physical and inorganic chemistry.
All topics
Paper I, physical and inorganic chemistry
Non-aqueous solvents: every question, 2021 to 2025
10 parts worth 82 marks have been set on this unit in UPSC IFoS Chemistry Paper I from 2021 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.
Syllabus
Reactions in liquid NH₃, HF, SO₂ and H₂SO₄. Failure of solvent system concept, coordination model of non-aqueous solvents. Some highly acidic media, fluorosulphuric acid and super acids.
Notes: Non-aqueous solvents: liquid NH₃, HF, H₂SO₄, SO₂, BrF₃ and superacids (full notes) · short notes
2025
- Q5(e) Reactions in nonaqueous media8 marks Answered
- Q8(c)(i) Conductance of metal–ammonia solutions5 marks Question only
- Q8(c)(ii) Blue colour in liquid ammonia5 marks Question only
2024
- Q6(c) Products in nonaqueous solvents10 marks Question only
2023
- Q5(e) Amphoteric salts in liquid sulfur dioxide8 marks Answered
- Q8(b) Reactions in liquid ammonia15 marks Question only
2022
- Q5(e) Fluorosulfuric acid and magic acid8 marks Answered
- Q8(b)(i) Sodium solutions in liquid ammonia10 marks Question only
- Q8(b)(ii) Reducing reactions of sodium–ammonia5 marks Question only
2021
- Q5(e) Acids behaving as bases in sulfuric acid8 marks Answered
Printed copy and Kindle
UPSC Indian Forest Service (Main) Chemistry Paper I: Model Answers 2021 to 2025
- All eight questions of each paper, with the question printed above its answer
- Physical chemistry numericals worked with units; inorganic structures drawn
- Topic-wise weightage and a topic-wise index