QJEEM25Chff18: JEE Main 2025 Chemistry - Class 12 JEEM25Chff18 Solution: Consider the following low-spin complexes The sum of the…

Yellow coloured \& low spin complex are $\mathrm{K}_3\left[\mathrm{Co}\left(\mathrm{NO}_2\right)_6\right] \& \mathrm{~K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]$

(I) $\quad \mathrm{K}_3\left[\mathrm{Co}\left(\mathrm{NO}_2\right)_6\right]$

$\mathrm{Co}^{+3} \Rightarrow[\mathrm{Ar}] 3 \mathrm{~d}^6$

In presence of ligand field

$\begin{aligned}\text { Magnetic moment } & =\sqrt{\mathrm{n}(\mathrm{n}+2)} \mathrm{BM} \\& =0 \mathrm{~BM}\end{aligned}$

$\begin{aligned}\text{(II) }\quad & \mathrm{K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right] \\& \mathrm{Fe}^{+2} \Rightarrow[\mathrm{Ar}] 3 \mathrm{~d}^6\end{aligned}$

In presence of ligand field

$\begin{aligned}\text { Magnetic moment } & =\sqrt{\mathrm{n}(\mathrm{n}+2)} \mathrm{BM} \\& =0 \mathrm{~BM}\end{aligned}$