Name of the type of isomerism exhibited by the following pairs of compounds: (1) and (2) and (3)…

Name of the type of isomerism exhibited by the following pairs of compounds: (1) $[\text{Co}(\text{ONO})(\text{NH}_3)_5]^{2+}$ and $[\text{Co}(\text{NO}_2)(\text{NH}_3)_5]^{2+}$ (2) $[\text{Cr}(\text{H}_2\text{O})_4\text{Cl}_2]\text{Cl}\cdot2\text{H}_2\text{O}$ and $[\text{Cr}(\text{H}_2\text{O})_5\text{Cl}]\text{Cl}_2\cdot\text{H}_2\text{O}$ (3) $[\text{Co}(\text{NH}_3)_6][\text{Cr}(\text{CN})_6]$ and $[\text{Cr}(\text{NH}_3)_6][\text{Co}(\text{CN})_6]$

Using the valence bond approach, predict the shape, hybridisation and magnetic behaviour of $[\text{Ni}(\text{CO})_4]$. (at. no. of $\text{Ni} = 28$)