Carbon dioxide dissolved in boiler water is dangerous in a modern power boiler because the gas __________.

Correct Answer: Option B — forms carbonic acid which attacks the watersides

Carbon dioxide dissolves in condensate and boiler water to form weak carbonic acid, lowering pH and causing aggressive grooving and general corrosion on internal metal watersides. Proper alkalinity control and degasification prevent this destructive acidic attack in marine power boilers.