Atmospheric Pollution

Scrubbers are air pollution control devices that play a crucial role in removing pollutants from industrial exhaust streams:

(A) Particulate SO₂ - Incorrect: SO₂ exists as a gas at normal conditions, not as particulate matter.

(B) Liquid SO₂ - Incorrect: Sulfur dioxide is only liquid under high pressure or low temperature conditions, not in typical industrial emissions.

(C) Gaseous SO₂ - Correct: Scrubbers are specifically designed to remove gaseous sulfur dioxide (SO₂) from flue gases through chemical reactions with alkaline slurries, typically forming calcium sulfite or sulfate.

(D) Liquid SO₃ - Incorrect: Sulfur trioxide (SO₃) typically reacts with water vapor to form sulfuric acid mist, not remaining as a liquid in exhaust streams.

The correct answer is (C) Gaseous SO₂, as scrubbers primarily target this major air pollutant from combustion processes through wet or dry scrubbing technologies.