Two methods of disinfection of municipal water are as follows  :

**1. By adding bleaching powder

      Bleaching powder reacts with water as,

      CaOCl2 + H2O → Ca(OH)2 + Cl2

        Cl2 + H2O → HCl + HOCl

                                              Hypochlorus acid

              HOCl → HCl + [O]

                                           Nascent oxygen**

In these reactions above, the …