Which pollutant is most commonly associated with acid rain?

Which pollutant is most commonly associated with acid rain?

• A. Carbon dioxide
• B. Methane
• C. Sulfur dioxide
• D. Ozone

Answer: (C)

Acid rain forms when certain air pollutants react with water in the atmosphere to produce acids that fall to the surface. The pollutant most linked to this is sulfur dioxide, released when sulfur-containing fuels like coal and oil are burned. In the air, sulfur dioxide is oxidized to sulfur trioxide and then combines with water to form sulfuric acid, a strong contributor to the acidity of precipitation. Nitrogen oxides also contribute by forming nitric acid, but sulfur dioxide is the more prominent and commonly cited precursor. Other options don’t fit the same pattern. Carbon dioxide dissolves in rain to form carbonic acid, but it’s a weaker acid and not the main driver of acid rain. Methane is a greenhouse gas with little role in acid rain formation, and ozone is a smog-related pollutant that doesn’t create acid rain.

Acid rain forms when certain air pollutants react with water in the atmosphere to produce acids that fall to the surface. The pollutant most linked to this is sulfur dioxide, released when sulfur-containing fuels like coal and oil are burned. In the air, sulfur dioxide is oxidized to sulfur trioxide and then combines with water to form sulfuric acid, a strong contributor to the acidity of precipitation. Nitrogen oxides also contribute by forming nitric acid, but sulfur dioxide is the more prominent and commonly cited precursor.

Other options don’t fit the same pattern. Carbon dioxide dissolves in rain to form carbonic acid, but it’s a weaker acid and not the main driver of acid rain. Methane is a greenhouse gas with little role in acid rain formation, and ozone is a smog-related pollutant that doesn’t create acid rain.