UPSC CSE Prelims
Question 24
Consider the following :
- Carbon monoxide
- Nitrogen oxide
- Ozone
- Sulphur dioxide
Excess of which of the above in the environment is/are cause(s) of acid rain ?
View correct answer and explanation
Correct answer: B
Correct Option: B (2 and 4 only)
Explanation: Acid rain forms largely when atmospheric nitrogen oxides and sulphur dioxide oxidise and dissolve to make nitric and sulphuric acids.
Statement / Pair / Item-wise Analysis:
1. False / does not qualify - Carbon monoxide is a pollutant but is not a principal precursor of acid rain.
2. True / qualifies - Nitrogen oxides form nitric acid in atmospheric reactions.
3. False / does not qualify - Ozone is an oxidant, not one of the two principal acid-rain precursors asked here.
4. True / qualifies - Sulphur dioxide forms sulphuric acid after oxidation.
Option-wise Analysis:
A. Incorrect-includes 1 even though Carbon monoxide is a pollutant but is not a principal precursor of acid rain.; includes 3 even though Ozone is an oxidant, not one of the two principal acid-rain precursors asked here.; omits 4 even though Sulphur dioxide forms sulphuric acid after oxidation.
B. Correct-selects exactly the correct statements/items identified above.
C. Incorrect-omits 2 even though Nitrogen oxides form nitric acid in atmospheric reactions.
D. Incorrect-includes 1 even though Carbon monoxide is a pollutant but is not a principal precursor of acid rain.; includes 3 even though Ozone is an oxidant, not one of the two principal acid-rain precursors asked here.; omits 2 even though Nitrogen oxides form nitric acid in atmospheric reactions.