Question

Match the complex in List-I with the number of unpaired electrons given in List-II.

Answer 1

Complex	Configuration	Unpaired electrons
$\left[Fe\right(H_{2}O{)}_6{]}^{2+}$	$\left[Ar\right]3d^6$	4
$\left[Fe\right(H_{2}O{)}_6{]}^{3+}$	$\left[Ar\right]3d^5$	5
$\left[Fe\right(CN{)}_6{]}^{4-}$	$\left[Ar\right]3d^6$	0
$\left[Fe\right(CN{)}_6{]}^{3-}$	$\left[Ar\right]3d^6$	1
$\left[Ni\right(H_{2}O{)}_4{]}^{2+}$	$\left[Ar\right]3d^8$	2

$C{N}^{-}$ is a strong field ligand, hence it will pair with the unpaired electrons.