$\therefore$ No of unpaired ${e}-({s})=0$

$\therefore \mu=\sqrt{n(n(n+2)}\,\, {BM}=0$

$[{n}=$ No of unpaired ${e}-({s})]$

In ${NiCl}_{2} {Ni}^{+2}$ is having configuration $3 {~d}^{8}$

$\therefore$ Number of unpaired electron $=2$

After formation of oxidised product

$\left[{Ni}({CN})_{6}\right]^{-2} {Ni}^{+4}$ is obtained

${Ni}^{{t}} \Rightarrow 3 {~d}^{6}$ and ${CN}^{-}$is strong field ligand

$\therefore$ number of unpaired electrons $=0$

$\therefore$ The charge is $2-0=2$