Disinfective action of chlorine is due to which of the following?

Ans. c (Hypochlorous acid) (Ref. Park Textbook of PSM 22nd/pg. 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 Horrock's apparatus).# Contact period of at least one hour is essential.# Minimum recommended concentration of free chlorine is 0.5 mg/lit 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.