\(\mathrm{Cr}_2 \mathrm{O}_3\) Amphoteric oxide

In \(\mathrm{CrO}, \mathrm{Cr}\) exist as \(\mathrm{Cr}^{+2}\) and have \(\mu\) only \(=4.90\)

In \(\mathrm{Cr}_2 \mathrm{O}_3, \mathrm{Cr}\) exist as \(\mathrm{Cr}^{+3}\) and have \(\mu\) only \(=3.87\)

Sum of spin only magnetic moment

\(=4.90+3.87=8.77\)

\(\mu_{\text {only }}=877 \times 10^{-2}\)

Ans. \(877\)