Chlorine water on standing loses its colour and forms: HCl only, HCl and HClO2, HCl and HOCl, HOCl and HOCl2

Chlorine water on standing loses its colour and forms HCl and HOCl. Cl2 + H2O → HCl + HOCl This is a disproportionation reaction. The hypochlorous acid so formed gives nascent oxygen which is responsible for oxidizing and bleaching properties of chlorine. Hence, option D is correct.