Question

Amongst the following ions which one has the highest magnetic moment value?

(i) $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$ (ii) $\left[Fe\right(H_{2}O{)}_6{]}^{2+}$ (iii) $\left[Zn\right(H_{2}O{)}_6{]}^{2+}$

Answer 1

The oxidation states of metals in the complexes along with the electronic configuration are given:
$C{r}^{3+}:3d^3$ configuration; no. of unpaired electrons (n) = 3
$F{e}^{2+}:3d^6$ configuration; n = 4
$Z{n}^{2+}:3d^{10}$ configuration; n = 0
The complex $\left[Fe\right(H_{2}O{)}_6{]}^{2+}$ with maximum number of unpaired electrons has the highest magnetic moment.