What is the color of the aqueous solution of $[Ni(H_2O)_6]^{2+}$?

The hybridisation and unpaired electrons in $[Fe(H_2O)_6]^{2+}$ ion are:

The hybridization states of the central atom in the complexes $[Fe(CN)_6]^{3-}$,$[Fe(CN)_6]^{4-}$ and $[Co(NO_2)_6]^{3-}$ are

Geometrical shapes of the complexes formed by the reaction of $Ni^{2+}$ with $Cl^{-}$,$CN^{-}$,and $H_2O$,respectively,are

On the basis of valence bond theory,discuss the geometrical shapes and magnetic properties of the following $4$-coordinated complexes:
$(i)$ $[NiCl_{4}]^{2-}$
$(ii)$ $[Ni(CN)_{4}]^{2-}$
$(iii)$ $[Ni(CO)_{4}]$
$(iv)$ $MnO_{4}^{-}$

Which of the following pairs of compounds is planar?