CuCl2 will dissolve in water to give blue colour Cu2+ ions. The colour is due to the presence of unpaired e− in Cu2+ ions. CuCl2+nH2O→
Cu2+(aq)
(Bluecolour)
AgCl and Cu2Cl2 are insoluble in water while ZnCl2 on dissolving in water forms colourless solution due to formation of Zn2+ ions, which has no unpaired e−.