Explain the complex species $[Ni(CN)_4]^{2-}$ on the basis of Valence Bond Theory $(VBT)$.

(N/A) In the complex $[Ni(CN)_4]^{2-}$,the central metal ion $Ni$ is in the $+2$ oxidation state. The electronic configuration of $Ni^{2+}$ is $3d^8$.
Since $CN^-$ is a strong field ligand,it causes the pairing of electrons in the $3d$ orbitals.
This results in one empty $3d$ orbital,one $4s$ orbital,and two $4p$ orbitals,which undergo $dsp^2$ hybridization to form four equivalent $dsp^2$ hybrid orbitals.
These four hybrid orbitals accept electron pairs from four $CN^-$ ligands.
Due to the presence of all paired electrons,the complex is diamagnetic.
Since it involves the inner $3d$ orbital,it is a low-spin or inner-orbital complex with a square planar geometry.