UPSC Combined Geo-Scientist, Mains · 2017 · Mains Paper I

Q1(g). CFCs and ozone depletion

5 marks
Topic: Outside the listed units
Answered

Question

Nowadays CFC (Chlorofluorocarbon)-free refrigerators are promoted in the market. Why and what is the consequence upon release of CFCs to the atmosphere? [Write only relevant reactions]

Answer in brief

CF₂Cl₂ →[hν] CF₂Cl• + Cl•

Key points

Cl• + O₃ → ClO• + O₂
ClO• + O → Cl• + O₂
Net: O₃ + O → 2O₂.

The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

Model answer to Q1(g), 2017 Mains Paper I: solution pages 3 and 4 — Solution pages 3 and 4 of 16

Read the whole 2017 solution 2017 question paper

CoversCFCsozone depletionEnvironmental chemistry

All parts of Question 1

1(a) Dichromate oxidation of iron5 marks
1(b) Phosphorus-doped silicon5 marks
1(c) Nickel magnetic moment5 marks
1(d) Eighteen-electron counts5 marks
1(e) Magic numbers5 marks
1(f) Dimethylberyllium bridges5 marks
1(g) CFCs and ozone depletion5 marks
1(h) Why thorium and uranium are well studied5 marks
1(i) Average and individual oxidation states5 marks
1(j) Mo and W radii5 marks