The coloured compound among the following in the solid state is:
1. \( \mathrm{Ag}_{2} \mathrm{SO}_{4} \)
2. \(\mathrm {C u F}_{2} \)
3. \(\mathrm {Zn F}_{2} \)
4. \(\mathrm{Cu}_{2} \mathrm{Cl}_{2} \)