Which of the following oxide gases are linked to acid rain according to the material?

• A. Both nitrogen oxides and sulfur oxides
• B. Nitrogen oxides only
• C. Sulfur oxides only
• D. Carbon dioxide

Answer: (A)

Acid rain is caused by oxides of sulfur and nitrogen dissolving in cloud droplets to form acids that lower the rain’s pH. Sulfur oxides from burning fossil fuels react in the atmosphere to form sulfurous and sulfuric acids, while nitrogen oxides react to form nitric acid. Because both types contribute to making the rain acidic, they’re both linked to acid rain. Carbon dioxide does dissolve in rain to make carbonic acid, but it’s not the main driver of acid rain in this context, so it’s not the primary link.