The oxidation state of Ni in [Ni(CN)4]2− is +2. The electronic configuration of Ni2+is[Ar]3d84s0. Ground stateNi2+ AsCN− is a strong field ligand, so it will pair up electrons [Ni(CN)4]2−
The hybridisation of Ni in [Ni(CN)4]2− is dsp2 and thus, it will a square planar geometry