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 ?

Acid rain is primarily caused by atmospheric pollutants, specifically sulfur dioxide (SO₂) and nitrogen oxides (NOx). These gases react with water, oxygen, and other chemicals in the atmosphere to form sulfuric acid and nitric acid. Statement 1 (Carbon monoxide) is incorrect. Carbon monoxide (CO) is a pollutant but does not cause acid rain. Statement 2 (Nitrogen oxide) is correct. Nitrogen oxides (NOx, including NO and NO₂) are major precursors to nitric acid formation in acid rain. Statement 3 (Ozone) is incorrect. Ozone (O₃) is a secondary pollutant and a greenhouse gas. While it can contribute to the oxidation processes that form acid rain from SO₂ and NOx, it is not a precursor acid gas itself and is not considered a primary cause in the same way as SO₂ and NOx. Statement 4 (Sulphur dioxide) is correct. Sulphur dioxide (SO₂) is a major precursor to sulfuric acid formation in acid rain.