UPSC Civil Services (Mains)
Chemistry optional
- 2 papers
- 250 marks each
- 3 h per paper
- 5 of 8 questions, Q1 and Q5 compulsory
Paper I covers physical and inorganic chemistry.
All years
Page 1 of 11 
Page 2 of 11 
Page 3 of 11 
Page 4 of 11 
Page 5 of 11 
Page 6 of 11 
Page 7 of 11 
Page 8 of 11 
Page 9 of 11 
Page 10 of 11 
Page 11 of 11
Paper I, physical and inorganic chemistry
Question paper, 2022
UPSC Civil Services (Mains), Chemistry optional. 11 pages, as issued by UPSC.
Every question of 2022, one page each38 parts in 8 questions, with the question as text and the key points of its answer
Question 1 50 marks
- 1(a)Average and most probable distance of the 1s electron10 marks
- 1(b)Non-bonding interactions between orbitals of A and B10 marks
- 1(c)F-centres: one colour by every route; effect on density10 marks
- 1(d)ΔG for the formation of ozone in smog10 marks
- 1(e)ΔG° and K for the zinc–copper cell reaction10 marks
Question 2 50 marks
Question 3 50 marks
- 3(a)The least stable of OCN⁻, ONC⁻ and SCN⁻10 marks
- 3(b)Entropy changes when an ice cube melts in the sea at 0 °C10 marks
- 3(c)Speed distribution curves of argon and helium10 marks
- 3(d)Phase diagram of water; critical point and triple point10 marks
- 3(e)Forces on an ion moving through a strong-electrolyte solution10 marks
Question 4 50 marks
- 4(a)The state of H₂ corresponding to N₂ at 126 K and 1 atm10 marks
- 4(b)Mean molar heat of vaporisation of water from two vapour pressures10 marks
- 4(c)Capillary rise of two liquids in the same tube10 marks
- 4(d)Principle of polarography; reading a polarogram10 marks
- 4(e)Percentage ionic character of the Br–Cl bond10 marks
Question 5 50 marks
- 5(a)Product concentration in a first-order reaction, N₂O₂ → 2NO10 marks
- 5(b)Jablonski diagram (A to E); the route to photochemistry10 marks
- 5(c)Allosteric effect and homotropic modulators10 marks
- 5(d)[Ni(CO)₄] and [Ni(CN)₄]⁴⁻: names, structures and shapes10 marks
- 5(e)Lower cyclosiloxanes: synthesis and structure of (Me₂SiO)₃10 marks
Question 6 50 marks
- 6(a)Metal–metal bonds in Cp₂Fe₂(CO)₄; structure of Bi₅³⁺10 marks
- 6(b)Pale colours and line-like spectra of lanthanide ions10 marks
- 6(c)Neutral mixed sandwich compound of a d⁶ centre10 marks
- 6(d)Separating XeF₆; diborane with NH₃ and with Me₃N10 marks
- 6(e)Origin of the yellow colour of aqueous FeCl₃10 marks
Question 7 50 marks
- 7(a)An optically active square-planar complex10 marks
- 7(b)Aqueous LaCl₃ and LuCl₃: which is more acidic10 marks
- 7(c)Opposing first-order reactions: time to form half the equilibrium amount10 marks
- 7(d)Surface area of an adsorbent from the nitrogen monolayer10 marks
- 7(e)Magnetic behaviour of copper(II) acetate and [Cu(CN)₄]³⁻10 marks
Question 8 50 marks
- 8(a)The more stable linkage isomer of a cyanide-bridged complex10 marks
- 8(b)Haemocyanin: active site, colours and functions10 marks
- 8(c)Stationary and branching chain reactions; conditions for explosion10 marks
- 8(d)Steady-state approximation; photochemical H₂ + Cl₂; quantum yield10 marks
- 8(e)Langmuir isotherm and the kinetics of surface reactions10 marks