UPSC Combined Geo-Scientist
Chemist
- 3 descriptive papers
- 200 marks each
- 3 h per paper
Mains Paper III covers analytical and organic chemistry.
All topics
Mains Paper III, analytical and organic chemistry
Analysis of geological materials: every question, 2016 to 2025
75 parts worth 492 marks have been set on this unit in UPSC Geo-Scientist Chemistry Mains Paper III from 2016 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.
Syllabus
Analysis of minerals and ores: estimation of (i) CaCO₃, MgCO₃ in dolomite (ii) Fe₂O₃, Al₂O₃ and TiO₂ in bauxite (iii) MnO and MnO₂ in pyrolusite. Analysis of metals and alloys: (i) Cu and Zn in brass (ii) Cu, Zn, Fe, Mn, Al and Ni in bronze (iii) Cr, Mn, Ni and P in steel (iv) Pb, Sb, Sn in 'type metal'. Introduction to petroleum: constituents and petroleum fractionation. Analysis of petroleum products: specific gravity, viscosity, Doctor test, aniline point, colour determination, cloud point, pour point. Determination of water, neutralization value (acid and base numbers), ash content, determination of lead in petroleum. Types of coal and coke, composition, preparation of sample for proximate and ultimate analysis, calorific value by bomb calorimetry.
Notes: Analysis of ores, alloys, petroleum, coal and coke (full notes) · short notes
2025
- Q1(g) Gravimetric estimation of nickel in steel5 marks Answered
- Q4(c) Ultimate analysis of coal: significance; estimation of ash10 marks Answered
- Q5(b) Aniline point, cloud point and pour point of petroleum products10 marks Question only
- Q5(c) Estimation of TiO₂ in bauxite5 marks Question only
2024
- Q1(g) Calorific value of a fuel5 marks Answered
- Q3(c) Theoretical oxygen demand; air for burning producer gas10 marks Question only
- Q5(c)(i) Ultimate analysis of a fuel; nitrogen by the Kjeldahl method10 marks Answered
- Q5(c)(ii) Fe₃O₄ in an ore by gravimetry5 marks Answered
2023
- Q3(c) Gross calorific value of coal from bomb calorimeter data5 marks Question only
- Q4(b) Alumina in bauxite by EDTA back-titration10 marks Answered
- Q5(d) Aniline point and Doctor test of petroleum products5 marks Answered
2022
- Q1(h) Manganese in pyrolusite by redox back-titration5 marks Answered
- Q3(b) Lead in petrol: direct and indirect methods10 marks Question only
- Q4(b) Proximate analysis of coal10 marks Answered
2021
- Q1(b) Ultimate analysis of coal5 marks Answered
- Q1(d) Gravimetric estimation of zinc in brass5 marks Answered
- Q2(b) Copper in brass by iodometric titration5 marks Answered
- Q3(b) CaCO₃ and MgCO₃ in dolomite by EDTA titration15 marks Question only
2020
- Q3(d) Moisture by Karl Fischer reagent10 marks Question only
- Q4(b) Sodium oxide in feldspar10 marks Answered
- Q5(a) Al and Mg from ignition of their oxinates5 marks Question only
- Q5(c) Balancing MnO₄⁻ + VO²⁺ in acid5 marks Question only
2019
- Q1(b) Nanomolar concentration to ppb5 marks Answered
- Q1(c) Buffer capacity and dilution5 marks Answered
- Q1(d) Washing the flask walls5 marks Answered
- Q1(f) Proximate coal analysis5 marks Answered
- Q1(g) Volumetric manganese in steel5 marks Answered
- Q2(a) Degree of hydrolysis and pH of 0.01 M Na₂CO₃10 marks Question only
- Q2(b) Bringing a sparingly soluble salt into solution10 marks Question only
- Q2(c) Why Eriochrome Black T fails for Cu²⁺, Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺, Al³⁺5 marks Question only
- Q2(d) Errors in iodine titrations with starch5 marks Question only
- Q3(c) Identifying and balancing redox5 marks Answered
- Q3(d) Errors from coprecipitation5 marks Answered
- Q3(e) Heavy-metal adsorption on hydrous oxides5 marks Answered
- Q4(a) Sulfur chloride formula5 marks Answered
- Q5(c) Estimation of Al₂O₃ in bauxite and Cu in brass10 marks Question only
2018
- Q1(a) Carbonate titration endpoint5 marks Answered
- Q1(b) Medium for iodimetry5 marks Answered
- Q1(c) Magnesium and the EBT endpoint5 marks Answered
- Q2(a) Co-precipitation and post-precipitation5 marks Question only
- Q2(b) Iodimetry and iodometry5 marks Question only
- Q2(d) Proximate and ultimate analysis of coal5 marks Question only
- Q2(e) Aniline point and cloud point5 marks Question only
- Q2(f) Primary and secondary standards5 marks Question only
- Q3(a) HCl and H₃PO₄ in a mixture by two end points10 marks Question only
- Q3(b) Sample weight of pyrite for a BaSO₄ factor weight10 marks Question only
- Q3(c)(i) Why the wash liquid is an electrolyte5 marks Question only
- Q3(c)(ii) Solubility of AgCl in 0.1 M NaNO₃5 marks Question only
- Q4(a) Chelation indicators10 marks Answered
- Q5(b) Manganese oxide equivalent10 marks Answered
- Q5(c) Nickel dimethylglyoximate10 marks Answered
2017
- Q1(a) Copper oxide mixture5 marks Answered
- Q1(b) Selective sulfate precipitation5 marks Answered
- Q1(c) Solvent effect on aniline basicity5 marks Answered
- Q3(b) Correlation index in petroleum analysis5 marks Question only
- Q4(a) Permanganate–chromate mixture10 marks Answered
- Q4(b) Free nickel with excess EDTA10 marks Answered
- Q4(c) Redox and acid–base indicators10 marks Answered
- Q5(a) Balanced net ionic equations10 marks Question only
- Q5(b) Empirical formula of a C, H, N, Cl compound10 marks Question only
- Q5(c) Equivalence point versus end point5 marks Question only
- Q5(d) Molarity and molality of 27% sulphuric acid5 marks Question only
2016
- Q1(a) Temperature and neutrality4 marks Answered
- Q1(e) Auxiliary complexing agent4 marks Answered
- Q1(g) DMG reagent requirement4 marks Answered
- Q2(a) Iodometric bleach assay5 marks Answered
- Q2(b) Analysis of brass constituents5 marks Answered
- Q2(c) Hydrated salt mixture5 marks Answered
- Q3(a) Iron reported as ferric oxide5 marks Answered
- Q3(c) Fully deprotonated fractions5 marks Answered
- Q4(a) [H₃O⁺] of a phosphoric acid–hydrogen phosphate buffer5 marks Question only
- Q4(b) CO₂ and H₂O from combustion of 4.635 mg benzoic acid5 marks Question only
- Q4(c) Acid–base indicators: methyl orange and phenolphthalein5 marks Question only
- Q5(b) Oxidising fusion test5 marks Answered
- Q6(c) Triiodide formation5 marks Answered
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UPSC Combined Geo-Scientist (Main) Chemistry Paper III: Model Answers 2021 to 2025
- All ten questions of each paper, with the question printed above its answer
- Instruments drawn as labelled diagrams, numericals worked with units
- Topic-wise weightage and a topic-wise index