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
General chemistry of 'f' block elements: every question, 2021 to 2025
10 parts worth 81 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
Lanthanides and actinides; separation, oxidation states, magnetic and spectral properties; lanthanide contraction.
Notes: Lanthanides and actinides: contraction, magnetism, spectra, separation (full notes) · short notes
Notes: Transition elements: 3d, 4d and 5d compared (radii, oxidation states, redox) (full notes) · short notes
2025
- Q8(b)(i) Lanthanide separation by valence change5 marks Question only
- Q8(b)(ii) Similarity of second and third transition series10 marks Question only
2024
- Q5(d) Relativity and lanthanide contraction8 marks Answered
- Q7(c) Divalent europium and samarium10 marks Question only
2023
- Q8(c)(i) Basicity of lanthanide hydroxides7 marks Question only
- Q8(c)(ii) Lanthanide moments and intense UV transitions8 marks Question only
2022
- Q7(c)(i) Lanthanide oxidation states8 marks Question only
- Q7(c)(ii) Sharp weak f–f spectra7 marks Question only
2021
- Q5(c) Separation of lanthanoids8 marks Answered
- Q8(c) Magnetic moments of Eu(III) and Sm(III)10 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