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
Outside the listed units: every question, 2016 to 2025
66 parts worth 575 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
Parts that test something not named in the syllabus.
2020
- Q2(a) Tetrasulphur tetranitride: preparation, structure, properties15 marks Question only
2019
- Q1(c) Diagonal relationship5 marks Answered
- Q1(d) Conductivity of phosphoric acid5 marks Answered
- Q1(f) Melting points of bromine and iodine chloride5 marks Answered
- Q1(g) Small dipole moment of CO5 marks Answered
- Q1(h) Acidity of concentrated HF5 marks Answered
- Q1(j) Diborane with excess ammonia5 marks Answered
- Q2(c) Lewis acidity of boron halides5 marks Answered
- Q3(a) Structures and pKa order of H₃PO₄, H₃PO₃ and H₃PO₂10 marks Question only
- Q3(b) Borazine: inorganic benzene, resonance and reactivity10 marks Question only
- Q3(d) Stability of +3 state of Al, Ga, In and Tl from E° values5 marks Question only
- Q7(a) Lattice energy of CaCl₂ by Born–Haber cycle10 marks Question only
- Q9(c) Cyanide bond order15 marks Answered
- Q10(a) Preparation of sodium borohydride5 marks Question only
- Q11(b) Amine oxide and phosphine oxide reactivity5 marks Answered
- Q11(c) Bronsted–Lowry concept10 marks Answered
2018
- Q1(a) Lithium hydride5 marks Answered
- Q1(d) Bronsted and Lewis acids5 marks Answered
- Q1(h) Alkali-ion selectivity of resins5 marks Answered
- Q1(i) Borazine and benzene5 marks Answered
- Q2(a) Electron affinity trends; near-zero values for Be, Mg, Ca and N10 marks Question only
- Q2(b) Basicity of ortho-, pyro- and metaphosphoric acids10 marks Question only
- Q2(c) Products of five p-block reactions10 marks Question only
- Q3(a) VSEPR prediction10 marks Answered
- Q3(b) Born–Haber cycle10 marks Answered
- Q3(c) MO diagrams of NO and CO10 marks Answered
- Q4(a) Ground terms by Hund's rules10 marks Answered
- Q5(c) Basicity order of CH₃⁻, NH₂⁻, OH⁻ and F⁻10 marks Question only
- Q6(a) Phosphorus disproportionation10 marks Answered
- Q6(b) Redox classification10 marks Answered
- Q9(a) Thermal decomposition of Li, Mg and Na salts; diagonal relationship15 marks Question only
- Q9(b) Basic beryllium acetate5 marks Question only
- Q9(c) Effective nuclear charge of the last electron in Na10 marks Question only
- Q10(a) Diborane from BF₃: structure, bonding, reactions with water and NH₃15 marks Question only
2017
- Q1(c) Nickel magnetic moment5 marks Answered
- Q1(f) Dimethylberyllium bridges5 marks Answered
- Q1(g) CFCs and ozone depletion5 marks Answered
- Q1(i) Average and individual oxidation states5 marks Answered
- Q2(a) VSEPR shapes10 marks Answered
- Q3(a) Chemical methods for extracting iron, copper and gold15 marks Question only
- Q3(b) Products of five inorganic reactions15 marks Question only
- Q6(a) Why B₂ is paramagnetic and C₂ diamagnetic10 marks Question only
- Q6(b) Br₂ and HCl with benzene and borazine10 marks Question only
- Q6(c) B–F π bonding in BF₃ versus BBr₃10 marks Question only
- Q7(a) Acidic and amphoteric oxides10 marks Answered
- Q7(b) Phosphorus oxide cages10 marks Answered
- Q7(c) Preparation and uses of silicones10 marks Answered
- Q10(a) Why NH₄Cl/NH₄OH cannot be replaced by NaCl/NaOH in Group III10 marks Question only
- Q11(a) pH control in sulfide separations10 marks Answered
2016
- Q1(a) Occurrence of lithium5 marks Answered
- Q1(b) Bond order and ionisation5 marks Answered
- Q1(c) Solvent levelling5 marks Answered
- Q1(d) Disproportionation and its reverse5 marks Answered
- Q1(f) Existence of hydrogen and helium dimers5 marks Answered
- Q1(i) Ground term and angular momenta5 marks Answered
- Q2(b) VSEPR theory: BeF₂, NH₃ and CCl₄15 marks Question only
- Q3(a) Terms of a d-squared configuration10 marks Answered
- Q5(a) Diagonal relationship10 marks Answered
- Q6(b) Lewis acids and bases10 marks Answered
- Q6(c) Acid strength and pH10 marks Answered
- Q7(c) Peroxy acids10 marks Question only
- Q8(a) Fluorocarbons: preparation, properties and uses15 marks Question only
- Q8(b) Shortest bond length among NO, NO⁻, NO⁺ and NO²⁺10 marks Question only
- Q8(c) Structure of diborane5 marks Question only
- Q10(a) Trends in group 1410 marks Answered
- Q11(a) SnCl₂ in HCl and NH₃; CO₂ vs SiO₂; SnCl₂ vs PbCl₂15 marks Question only
Printed copy and Kindle
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