The number of geometrical isomers found in the metal complexes $\left[\mathrm{PtCl}_2\left(\mathrm{NH}_3\right)_2\right],\left[\mathrm{Ni}(\mathrm{CO})_4\right],\left[\mathrm{Ru}\left(\mathrm{H}_2 \mathrm{O}\right)_3 \mathrm{Cl}_3\right]$ and $\left[\mathrm{CoCl}_2\left(\mathrm{NH}_3\right)_4\right]^{+}$respectively, are :
