<prompt> Which pa of chlorine disinfection is most effective?-Hypochlorous acidHypochlorous ionHypochlorite ionNone  <response>: 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 