# According to molecular orbital theory, the number of unpaired

Question:

According to molecular orbital theory, the number of unpaired electron(s) in $\mathrm{O}_{2}^{2-}$ is :

Solution:

Molecular orbital configuration of $\mathrm{O}_{2}^{2-}$ is

$\sigma_{1 \mathrm{~s}}^{2} \sigma_{1 \mathrm{~s}}^{* 2} \sigma_{2 \mathrm{~s}}^{2} \sigma_{2 \mathrm{~s}}^{* 2}\left(\pi 2 \mathrm{p}_{\mathrm{x}}^{2}=\pi 2 \mathrm{p}_{\mathrm{y}}^{2}\right)\left(\pi_{2 \mathrm{px}}^{* 2}=\pi_{2 \mathrm{py}}^{* 2}\right)$

Zero unpaired electron