Chemistry - Complete d-block Question with Solution | TestHub

The electronic configuration of the given cations and their number of unpaired electrons ($n$) are as follows:

${\text{Ni}}^{2+}$ ($Z=28$): $[\text{Ar}]3d^8$, $n=2$

${\text{Zn}}^{2+}$ ($Z=30$): $[\text{Ar}]3d^{10}$, $n=0$

${\text{Fe}}^{3+}$ ($Z=26$): $[\text{Ar}]3d^5$, $n=5$

${\text{Sc}}^{2+}$ ($Z=21$): $[\text{Ar}]3d^1$, $n=1$

${\text{Fe}}^{3+}$ has the maximum number of unpaired electrons.

Answer: ${\text{Fe}}^{3+}$