Bleaching action of chlorine is due to its oxidizing property. When chlorine reacts with water, it gives nascent oxygen which decoloures is the coloured substance.
Cl2 + H2O → 2HCl + [O]
Coloured substance + [O] → Colourless substance
Bleaching action of chlorine creates permanent effect. It bleaches the vegetable of organic matter in the presence of moisture.
