Name three common boiler water treatment chemicals and their roles.

• A. Oxygen scavengers remove dissolved oxygen; alkalinity buffering agents control pH; scale inhibitors/dispersants prevent scale and sludge buildup.
• B. Corrosion inhibitors form protective films; anti-foam agents reduce foaming; chelating agents remove minerals.
• C. Acid cleaners dissolve mineral deposits; biocides kill bacteria; demineralizers remove hardness.
• D. pH meters measure acidity; silica filters remove particulates; biocides kill bacteria.

Answer: (A)

The key idea here is that boiler water treatment focuses on three core chemical roles to protect the system: removing dissolved oxygen to prevent corrosion, buffering alkalinity to control pH and reduce corrosive conditions, and preventing mineral scale and sludge by keeping deposits from forming. Oxygen scavengers chemically remove dissolved oxygen from the feedwater, so iron and steel components don’t corrode. Alkalinity buffering agents maintain an alkaline pH that minimizes corrosive conditions and supports protective oxide films on metal surfaces. Scale inhibitors and dispersants keep minerals from forming hard scale or clumping into sludge, preserving heat transfer efficiency. Other options involve important but different tools—like corrosion inhibitors, anti-foam agents, or chelating agents used in various contexts, maintenance cleaners, or instrumentation—yet they don’t address these three fundamental chemical actions in this typical boiler-water treatment framework. Therefore, the combination of oxygen removal, pH control, and anti-scale/anti-sludge action is the best fit.