Question:easy
The active disinfectant property of bleaching powder is due to:
The active disinfectant property of bleaching powder is due to:
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Chlorine reacts with water to form the actual germicidal acid.
Updated On: Jun 23, 2026
- Chlorine
- Hypochloric acid
- Hypochlorous acid
- Chloramines
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The Correct Option is C
Solution and Explanation
Clinical-pearl approach: the germ killing in chlorination is done by the small neutral molecule HOCl, not by chlorine gas itself.
Bleaching powder (CaOCl2) puts chlorine into the water. That chlorine immediately reacts with water and the key product is hypochlorous acid. Because HOCl carries no charge and is small, it slips through the bacterial cell membrane and oxidises vital enzymes, which is why it is the most potent disinfecting form. The hypochlorite ion OCl- helps a little but is charged and far less effective.
Reject the distractors: plain chlorine is only the source, chloramines (chlorine plus ammonia) are weaker and slower combined chlorine, and hypochloric acid is not a real disinfecting agent. The active killer is hypochlorous acid. Ref: Park PSM, 24e.
Bleaching powder (CaOCl2) puts chlorine into the water. That chlorine immediately reacts with water and the key product is hypochlorous acid. Because HOCl carries no charge and is small, it slips through the bacterial cell membrane and oxidises vital enzymes, which is why it is the most potent disinfecting form. The hypochlorite ion OCl- helps a little but is charged and far less effective.
Reject the distractors: plain chlorine is only the source, chloramines (chlorine plus ammonia) are weaker and slower combined chlorine, and hypochloric acid is not a real disinfecting agent. The active killer is hypochlorous acid. Ref: Park PSM, 24e.
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