Step 1: Find the electronic configuration of \(\mathrm{Fe}^{2+}\).
Atomic number of iron is
\[
26
\]
Electronic configuration of neutral iron is
\[
\mathrm{Fe}: [Ar]\,3d^6\,4s^2
\]
For \(\mathrm{Fe}^{2+}\), two electrons are removed from \(4s\) orbital.
Therefore,
\[
\mathrm{Fe}^{2+}: [Ar]\,3d^6
\]
Step 2: Find the number of unpaired electrons.
For \(3d^6\) configuration in high spin state, the number of unpaired electrons is
\[
n=4
\]
Step 3: Use the spin-only magnetic moment formula.
The magnetic moment is
\[
\mu=\sqrt{n(n+2)}
\]
Substitute
\[
n=4
\]
\[
\mu=\sqrt{4(4+2)}
\]
\[
\mu=\sqrt{24}
\]
\[
\mu=4.90\,\text{BM}
\]
Step 4: Final conclusion.
Hence, the calculated magnetic moment of \(\mathrm{Fe}^{2+}\) is
\[
\boxed{4.90\,\text{BM}}
\]