Scrubbers are:

• A. A machine that moves gases through a spray of water that dissolves many pollutants
• B. A device that measures pH levels
• C. A filter that traps dust particles
• D. A device that compresses air

Answer: (A)

Scrubbers clean polluted gas by forcing the gas to flow through a spray of water or other liquid, so soluble pollutants dissolve into the liquid. This gas–liquid contact transfers contaminants from the gas into the liquid, leaving the gas much cleaner as it exits. This wet scrubbing process is specifically about dissolving pollutants, not about measuring pH, trapping dust with a filter, or compressing air, which are different functions.