<prompt> Disinfective action of chlorine is due to which of the following?HypochloriteHypochlorineHypochlorous acidNone  <response>: Ans. c Hypochlorous acid Ref. Park Textbook of PSM 22ndpg. 663.CHLORINATION: Disinfective action of chlorine is mainly due to Hypochlorous acid and to a small extent due to theHypochlorous ions. H2O Cl2 r HCI HOCI. HOCI r H OCI Chlorine acts best when pH of water is 7.Principles of chlorination are: Water should be clear free from turbidity. Chlorine demand of water should be estimated done by Horrocks apparatus. Contact period of at least one hour is essential. Minimum recommended concentration of free chlorine is 0.5 mglit for one hour.BREAK POINT CHLORINATION - the point at which the residual chlorine appears and when all combined chlorine has been completely destroyed. 33 available chlorine should be there in bleaching powder. 