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
Surface phenomena and catalysis: every question, 2021 to 2025
7 parts worth 66 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
Adsorption from gases and solutions on solid adsorbents, adsorption isotherms: Langmuir and B.E.T. isotherms; determination of surface area, characteristics and mechanism of reaction on heterogeneous catalysts.
Notes: Adsorption, heterogeneous catalysis and colloids (full notes) · short notes
2025
- Q5(b) Langmuir adsorption isotherm8 marks Answered
- Q6(b)(ii) Heterogeneous catalysis5 marks Answered
2024
- Q4(c) BET surface-area measurement10 marks Answered
2023
- Q6(c) Catalysts and the Freundlich isotherm10 marks Answered
2022
- Q5(b) Fractional surface coverage8 marks Answered
- Q7(a) Adsorption isotherms and BET theory10 marks Question only
2021
- Q7(a) Langmuir adsorption and the Freundlich form15 marks Question only
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