Indian Forest Service (Mains)
Chemistry optional
- 2 papers
- 200 marks each
- 3 h per paper
Paper I covers physical and inorganic chemistry.
All years
Pages 1 and 2 of 30 
Pages 3 and 4 of 30 
Pages 5 and 6 of 30
Pages 7 and 8 of 30 Pages 9 and 10 of 30 Pages 11 and 12 of 30 Pages 13 and 14 of 30 Pages 15 and 16 of 30 Pages 17 and 18 of 30 Pages 19 and 20 of 30 Pages 21 and 22 of 30 Pages 23 and 24 of 30 Pages 25 and 26 of 30 Pages 27 and 28 of 30 Pages 29 and 30 of 30
Paper I, physical and inorganic chemistry
Solution, 2016
Indian Forest Service (Mains), Chemistry optional. 30 pages. Questions 1, 2, 4, 5 and 7 are answered.
Every question of 2016, one page each45 parts in 8 questions, with the question as text and the key points of its answer
Question 1 40 marks
- 1(a)(i)Bond angle of F₂O smaller than that of H₂O5 marks
- 1(a)(ii)Residual entropy of CO and N₂O at 0 K5 marks
- 1(b)(i)Activation energy from rate constants at two temperatures5 marks
- 1(b)(ii)Ionic strength of 0.01 m H₂SO₄ + 0.02 m NaCl5 marks
- 1(c)Heat of reaction at 120°C: Kirchhoff's law10 marks
- 1(d)(i)Crystal systems with mutually perpendicular axes5 marks
- 1(d)(ii)Spacing of the (110) planes, axes mutually perpendicular5 marks
Question 2 40 marks
Question 3 40 marks
- 3(a)(i)Polarography: principle, half-wave potential, resolving close waves10 marks
- 3(a)(ii)Magnetic data and the structure of lanthanide complexes10 marks
- 3(b)(i)Phase, component and degree of freedom5 marks
- 3(b)(ii)Components of aqueous NaCl + KBr, then with KCl and NaBr5 marks
- 3(c)Rate constants of C ⇌ D from the relaxation time and K10 marks
Question 4 40 marks
Question 5 40 marks
- 5(a)(i)Fluorescence5 marks
- 5(a)(ii)Chemiluminescence5 marks
- 5(b)(i)Chelate effect5 marks
- 5(b)(ii)Lability5 marks
- 5(c)(i)Actinide spectra and the ligand5 marks
- 5(c)(ii)Co²⁺ salts stable, Co²⁺ complexes easily oxidised5 marks
- 5(d)(i)Shapes of the d orbitals5 marks
- 5(d)(ii)Splitting of d orbitals in a square-planar field5 marks
Question 6 40 marks
- 6(a)(i)Crystal field stabilisation energy and the factors that fix it10 marks
- 6(a)(ii)CFSE and magnetic moments of FeCl₃.6H₂O and K₄[Fe(CN)₆]10 marks
- 6(b)(i)General electronic configurations of the 4f and 5f elements5 marks
- 6(b)(ii)Lanthanide contraction; effect on 4f and 5d chemistry5 marks
- 6(c)(i)IUPAC names of two complexes5 marks
- 6(c)(ii)Ce³⁺ colourless, Ti³⁺ purple5 marks
Question 7 40 marks
With any Mains test series
Read the full model answer to every question of this paper with a Mains test series
Every Mains test series (Civil Services, IFoS or Geo-Scientist) opens the solved IFoS Mains PYQ answers, the notes, the handbook and the daily answer archive until your Mains. The first test of each series is free. Civil Services and Geo-Scientist Mains PYQ solutions and Geo-Scientist Prelims PYQ solutions are free for everyone.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.
Model answer pages open with any Mains test series.