Manganese (Mn) has an atomic number of 25.
The electronic configuration of Mn is: \([Ar] \, 3d^5 \, 4s^2\).
Mn\(^{3+}\) loses 3 electrons, resulting in the configuration \([Ar] \, 3d^4\).
The number of unpaired electrons in \(3d^4\) is 4.
The magnetic moment \( \mu \) is calculated using the formula \( \mu = \sqrt{n(n+2)} \, \text{BM} \), where \(n\) represents the number of unpaired electrons.
\[
\mu = \sqrt{4(4+2)} = \sqrt{24} \approx 4.90 \, \text{BM}
\]