Question

The substances which contain species with unpaired electrons in
their orbitals behave as paramagnetic substances. Such substances
are weakly attracted by the magnetic field. The paramagnetism is
expressed in terms of magnetic moment. The magnetic moment is
related to the number of unpaired electrons according to the
following relation:
Magnetic moment, $\mu =\sqrt{n(n+2)}BM$
where, $n=$ number of unpaired electrons.
$BM$ stands for Bohr magneton, a unit of magnetic moment.
$1BM=\frac{eh}{4\pi mc}=9.27\times {10}^{-24}{Am}^2$ or $J{T}^{-1}$

Which of the following ions has the highest magnetic moment?

• A. ${Fe}^{2+}$
• B. ${Mn}^{2+}$
• C. ${Cr}^{3+}$
• D. $V^{3+}$

Answer 1

The correct option is B ${Mn}^{2+}$

$M{n}^{2+}$ ion has the highest magnetic moment as it has maximum number of unpaired electrons.
$F{e}^{2+}3d^{4}4$ unpaired electrons.
$M{n}^{2+}3d^{5}5$ unpaired electrons.
$C{r}^{3+}3d^{3}3$ unpaired electrons.
$V^{3+}3d^{2}2$ unpaired electrons.
Greater is the number of unpaired electrons, greater is the magnetic moment.