Moist chlorine gives nascent oxygen, act as oxidising
agent:
$\, \, \, \, \, \, \, \, \, \, \, \, Cl_2 + H_2O \longrightarrow HCl + HOCl$
$\, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, HOCl \longrightarrow HCl+\, \, \, \, ^{\, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, [O]}_{nascent\, oxygen\, (bleaching action)}$