QJEEM21Ch63db: JEE Main 2021 Chemistry - Class 12 JEEM21Ch63db Solution: Spin only magnetic moment of an octahedral complex of Fe 2+ in…

In presence of SFL $\Delta$ ₀ > P means pairing occurs therefore

For Fe⁺² $\to$ 3d⁶



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

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

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

In NiCl₂, Ni⁺² is having configuration 3d⁸

$\therefore$ Number of unpaired electron = 2

After formation of oxidised product

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

Ni⁺⁴ $\Rightarrow$ 3d⁶ and CN ^$-$ is strong field ligand

$\therefore$ Number of unpaired electrons = 0

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