Among $\left[\mathrm{Ni}{\left(\mathrm{CO}\right)}_4\right], [\mathrm{Ni}{\left(\mathrm{CN}\right)}_4{]}^{-2} \mathrm{and} {\left[{\mathrm{NiCl}}_4\right]}^{-2}$ species the hybridization state of the $\mathrm{Ni}$ atom are respectively?

• The $\left[\mathrm{Ni}{\left(\mathrm{CO}\right)}_4\right]$ complex has an outermost electronic configuration of $3{\mathrm{d}}^{2}4{\mathrm{s}}^2$ and since $\mathrm{CO}$ is a potent ligand, electrons pair up and exhibit ${\mathrm{sp}}^3$  hybridization.  
• The $[\mathrm{Ni}{\left(\mathrm{CN}\right)}_4{]}^{-2}$complex has an outermost electronic configuration of $3{\mathrm{d}}^8$, and $\mathrm{CN}$ since  is a powerful ligand, electrons pair up but one d orbital is vacant and exhibits ${\mathrm{dsp}}^2$ hybridization.
•  The$[\mathrm{Ni}{\left(\mathrm{Cl}\right)}_4{]}^{-2}$ complex's outermost electronic configuration is$3{\mathrm{d}}^{8}4{\mathrm{s}}^2,$and Cl is a weak ligand, therefore electrons are not coupled up and exhibit ${\mathrm{sp}}^3$ hybridization.

Hence, the correct option is option (B) ${\mathrm{sp}}^3, {\mathrm{dsp}}^2, {\mathrm{sp}}^3$.