Percentage available chlorine from bleaching powder is:-: (A) 10%, (B) 33%, (C) 66%, (D) 95%
Answer is B. Bleaching powder contains : 33% available chlorine. Bleaching powder required for disinfection of 1000 litres of water = 2.5 grams. Also Remember, Free/ residual chlorine levels recommended in:- Drinking water = >= 0.5 mg/ L ; with contact period of 1hr. Drinking water to kill cyclops = >= 2.0 mg/L ; with contact period of 1hr. Swimming pools of India =>= 1.0 mg/L ; with contact period of 1hr.