Acid rain is caused due to emission of which of the following into the atmosphere?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Oxides of nitrogen and sulfur dioxide
Acid rain is rain with a pH below about 5.6. Burning coal and oil in power plants, factories and vehicles releases sulfur dioxide (\(\ce{SO2}\)) and oxides of nitrogen (\(\ce{NO_x}\)). In the air they react with water and oxygen to form sulfuric acid and nitric acid, which come down with rain.
Why the other options are incorrect
Option (2) Carbon dioxide and carbon monoxide — Incorrect. \(\ce{CO2}\) forms only the weak carbonic acid that makes normal rain pH 5.6, and \(\ce{CO}\) is a poisonous gas, not an acid-former.
Option (3) Ozone and carbon dioxide — Incorrect. Ozone near the ground is a smog pollutant, and neither gas forms strong acids in rain.
Option (4) Carbon monoxide and nitrogen — Incorrect. Nitrogen gas is inert and makes up 78% of air; only its oxides cause acid rain.