10gm sample of bleaching powder was dissolved into water to make the solution on litre. To this solution 35 mL of 1.0 M Mohr salt solution was added containing enough H₂SO₄. After the reaction was complete, the excess Mohr salt required 30mL of 0.1M KMnO₄ for oxidation. The % of available Cl2 approximately is ( mol wt = 71)