Which gas is primarily responsible for the formation of acid rain when it reacts with water in the atmosphere?

Solution

1. ${\text{SO}}_2$ is released into the atmosphere from the combustion of fossil fuels.
2. It reacts with atmospheric oxygen and water as $2{\text{SO}}_2+{\text{O}}_2+2{\text{H}}_2\text{O}\to 2{\text{H}}_2{\text{SO}}_4$.
3. The resulting sulfuric acid contributes to the acidity of rain.
4. Hence the answer is (B).