UPSC Combined Geo-Scientist
Chemist
- 3 descriptive papers
- 200 marks each
- 3 h per paper
Mains Paper I covers inorganic chemistry.
All topics
Mains Paper I, inorganic chemistry
Organometallic compounds: every question, 2016 to 2025
38 parts worth 340 marks have been set on this unit in UPSC Geo-Scientist Chemistry Mains Paper I from 2016 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.
Syllabus
18-electron rule and its applications to carbonyls and nature of bonding involved therein. Simple examples of metal-metal bonded compounds and metal clusters. Wilkinson's catalyst.
Notes: Organometallics: 18-electron rule, oxidative addition, Wilkinson's catalyst (full notes) · short notes
Notes: Metal carbonyls, nitrosyls, 18-electron rule and metal clusters (full notes) · short notes
2025
- Q4(a) Wilkinson’s catalyst; hydrogenation cycle15 marks Answered
- Q4(b) 18-electron rule: [(η⁶-C₆H₆)Cr(CO)₃] and [(CO)₂Rh(μ-Cl)₂Rh(CO)₂]10 marks Answered
2024
- Q1(h) Terminal and bridging carbonyl bands5 marks Answered
- Q5(a) A face-capped trinickel carbonyl cluster10 marks Answered
- Q7(a) Oxidative addition and reductive elimination10 marks Question only
- Q7(b)(i) Two forms of dicobalt octacarbonyl5 marks Question only
- Q7(b)(ii) Tetrahedral Ir₄(CO)₁₂5 marks Question only
2023
- Q1(c) Effective atomic numbers5 marks Answered
- Q1(i) Back-donation and carbonyl stretching5 marks Answered
- Q9(a) The 18-electron rule in metal carbonyls15 marks Question only
- Q9(b) Wilkinson-catalysed alkene hydrogenation10 marks Question only
- Q9(c) Preparation of Wilkinson’s catalyst5 marks Question only
2022
- Q1(h) Carbonyl ligand counts5 marks Answered
- Q9(a) Electron counts and metal-metal bonds10 marks Question only
- Q9(b) Structures and bonding of iron carbonyl clusters15 marks Question only
- Q9(c) Substitution in vanadium carbonyls5 marks Question only
2021
- Q1(h) Carbonyl C-O bond strengths5 marks Answered
- Q9(a)(i) Catalytically useful features of Wilkinson’s complex5 marks Answered
- Q9(a)(ii) Alkene hydrogenation by Wilkinson’s catalyst10 marks Answered
- Q9(b) Quadruple bonding in octachlorodirhenate15 marks Answered
2020
- Q1(g) Triiron dodecacarbonyl5 marks Answered
- Q9(b) Wilkinson's catalyst: propene hydrogenation cycle15 marks Question only
2019
- Q4(c) Stability of nickel carbonyl10 marks Answered
- Q6(c) Zeise's salt structure10 marks Answered
- Q7(b) Isomers of Co₂(CO)₈ and their Co–Co bonds10 marks Question only
- Q7(c) Products of five inorganic and organometallic reactions10 marks Question only
2018
- Q1(f) Predicting carbonyl numbers5 marks Answered
- Q7(b) Synthesis of mixed metal carbonyl nitrosyls5 marks Question only
- Q7(c) Structure and bonding of ferrocene10 marks Question only
2017
- Q1(d) Eighteen-electron counts5 marks Answered
- Q8(a) Metal–metal bonds from electron counts15 marks Answered
- Q8(b) Zeise's salt and alkene bonding15 marks Answered
- Q9(a) Cr(CO)₆ monomer but Mn₂(CO)₁₀ dimer10 marks Question only
- Q9(b) C–C distances in a Rh(C₂H₄)(C₂F₄) complex10 marks Question only
- Q9(c) Products of a nucleophilic addition10 marks Question only
2016
- Q1(j) Effective atomic number5 marks Answered
- Q4(c) Structure and bonding in Fe₃(CO)₁₂10 marks Question only
- Q5(c) Bonding in metal carbonyls10 marks Answered
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UPSC Combined Geo-Scientist (Main) Chemistry Paper I: Model Answers 2021 to 2025
- All eleven questions of each paper, with the question printed above its answer
- Titration, gravimetric and nuclear numericals worked with units; structures drawn
- Topic-wise weightage and a topic-wise index