Question:
The bond order and magnetic behaviour of $\mathrm{O}_{2}^{-}$ion are, respectively:
Correct Option: 1
Solution:
$\mathrm{O}_{2}^{-}=\left(\sigma_{1 \mathrm{~s}}\right)^{2}\left(\sigma_{1 \mathrm{~s}}^{*}\right)^{2}\left(\sigma_{2 \mathrm{~s}}\right)^{2}\left(\sigma_{2 \mathrm{~s}}^{*}\right)^{2}\left(\sigma_{2 \mathrm{p}_{\mathrm{z}}}\right)^{2}$
$\left(\pi_{2 p_{x}}^{2}=\pi_{2 p_{y}}^{2}\right)\left(\pi_{2 p_{x}}^{* 2}=\pi_{2 p_{y}}^{*_{1}}\right)$
Bond order $=\frac{10-7}{2}=1.5$