d and f Block Elements Part 1

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−.