Acid rain main pollutants – UGC NET Question

Acid rain forms when sulphur dioxide and nitrogen oxides released from combustion processes react with water vapour and oxidants in the atmosphere. These reactions produce sulphuric and nitric acids that are deposited as wet or dry precipitation. The resulting acidic deposition damages forests, aquatic ecosystems, soils and built structures. Therefore, the pairing of sulphur dioxide and nitrogen oxides is recognised as the principal cause of acid rain.

Option A:
Option A is incorrect because carbon monoxide and ozone play different roles in air pollution. Carbon monoxide is a toxic gas affecting human health, and ground-level ozone is a component of photochemical smog, but they are not the main precursors of strong acids in rainwater. Their chemistry does not primarily create acidic precipitation.

Option B:
Option B correctly names the gases that transform into sulphuric and nitric acids when they dissolve in cloud droplets. These gases are emitted largely from coal-based power plants, industrial boilers and vehicles, and controlling them is central to acid rain mitigation strategies.

Option C:
Option C is incorrect since methane is more associated with greenhouse effects, and chlorofluorocarbons are linked to ozone depletion and climate forcing. Neither group is directly responsible for the formation of the strong acids that cause acid rain in most regions.

Option D:
Option D is incorrect because hydrogen and helium are light gases that do not form acidic compounds in the atmosphere under normal environmental conditions. They are not significant contributors to rain chemistry or ecosystem acidification.