Which of the following is an example of wet deposition?

• A. Sulfate deposition in rain.
• B. Dust on leaves.
• C. Ozone concentration.
• D. Dry deposition of methane.

Answer: (A)

Wet deposition is the removal of atmospheric pollutants by precipitation, such as rain, snow, or fog, when those pollutants are dissolved in the rain drops and deposited on surfaces. Sulfate deposition in rain is a classic example because sulfate ions formed or scavenged in the atmosphere are carried down to the surface with the rain, delivering them via precipitation. In contrast, dust on leaves happens without precipitation—it's dry deposition, where particles settle onto surfaces directly. Ozone concentration describes a gas in the air, not a deposition process, and dry deposition of methane involves uptake by surfaces without rain.