Which pa of chlorine disinfection is most effective?-: (A) Hypochlorous acid, (B) Hypochlorous ion, (C) Hypochlorite ion, (D) None
Answer is A. The disinfecting action of chlorine is mainly due to hypochlorous acid. It is 70-80 times effective than hypochlorite ion. So chlorine acts as best disinfectant a when pH of water is around 7 because of the predominance of hypochlorous acid. (PARK TB 25th edition pg 774)