Household bleach contains hypochlorite ion, which is formed when chlorine dissolves in water. The determine the concentration of hypochlorite in the bleach, the solution is first treated with a Kl solution. The iodine liberated can be determined by titration with a standard thiosulphate solution. A 25 ml of certain household bleach requires 17.4 ml of a 0.2 M Na, S2O3 solution for titration. The mass of chlorine dissolved in one litre of the bleach solution is (A) 0.1392 g (B) 0.494 g