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
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Paper I, physical and inorganic chemistry
Question paper, 2023
UPSC Civil Services (Mains), Chemistry optional. 12 pages, as issued by UPSC.
Every question of 2023, one page each36 parts in 8 questions, with the question as text and the key points of its answer
Question 1 50 marks
- 1(a)Light emitted by a particle in a box; the uncertainty principle10 marks
- 1(b)Lewis structures of [Br₃]⁻ and thiourea; the most polar bond10 marks
- 1(c)Bragg equation and the layer spacing10 marks
- 1(d)Root-mean-square speed of water molecules10 marks
- 1(e)(i)E° of Cr³⁺/Cr from two couples5 marks
- 1(e)(ii)Surface tension, contact angle and loss of gravity5 marks
Question 2 50 marks
Question 3 50 marks
Question 4 50 marks
Question 5 50 marks
Question 6 50 marks
Question 7 50 marks
- 7(a)Haemoglobin and cytochrome c; oxy- and deoxyhaemoglobin10 marks
- 7(b)Configurations of Pr, Eu and Gd and the moments of their M³⁺ ions10 marks
- 7(c)Rate expression for a bimolecular surface reaction10 marks
- 7(d)Electronic spectrum of [Ni(OS(CH₃)₂)₆]²⁺10 marks
- 7(e)Reversible isothermal expansion of an ideal gas10 marks