Which pollutants contribute to acid rain and what are their sources?

• A. Sulfur dioxide from burning sulfur-containing fuels and nitrogen oxides from vehicles and power stations.
• B. Oxygen from air and nitrogen from the atmosphere; no pollution source.
• C. Chlorine from pools and carbon from carbonated drinks.
• D. Hydrogen from fuels and helium from balloons.

Answer: (A)

Acid rain comes from pollutants that dissolve in rain and make acids. The main culprits are sulfur dioxide and nitrogen oxides. Sulfur dioxide is released when fuels that contain sulfur, like coal and some heavy oils, are burned in power stations and other industrial processes. Nitrogen oxides are formed during high-temperature combustion in vehicles and in power stations. In the atmosphere, these gases react with water and oxygen to produce sulfuric acid and nitric acid, which lower the rain’s pH. That’s why emissions from cars, factories, and electricity generation are linked to acid rain. The other options don’t fit because oxygen and nitrogen in the air don’t by themselves create acidic rain, and chlorine, carbon, hydrogen, or helium aren’t the pollutants responsible for acid rain.