The bond order and magnetic

$\mathrm{O}_{2}^{-}=\left(\sigma_{1 \mathrm{~s}}\right)^{2}\left(\sigma_{1 \mathrm{~s}}^{*}\right)^{2}\left(\sigma_{2 \mathrm{~s}}\right)^{2}\left(\sigma_{2 \mathrm{~s}}^{*}\right)^{2}\left(\sigma_{2 \mathrm{p}_{\mathrm{z}}}\right)^{2}$

$\left(\pi_{2 p_{x}}^{2}=\pi_{2 p_{y}}^{2}\right)\left(\pi_{2 p_{x}}^{* 2}=\pi_{2 p_{y}}^{*_{1}}\right)$

Bond order $=\frac{10-7}{2}=1.5$