Question

The number of antibonding electron pairs in $O_2^{2-}$ molecular ion on the basis of molecular orbital theory is (at. no. of $O$ is $18$)

• A. 5
• B. 2
• C. 4
• D. 6

Answer 1

Answer: (C)

4

Answer 2

The electronic configuration of $O _{2}^{2-}$ ion is
$O _{2}^{2-}-\sigma ls ^{2}, \sigma^{*} ls ^{2}, \sigma 2 s^{2}, \sigma{*}\, 2 s^{2}, \sigma 2 p_{z}^{2}, \sigma 2 p_{x}^{2} \pi 2 p_{y}^{2}, \,\pi^{*} \, 2 p_{x}^{2}, \pi 2 p_{y}^{2}$
Hence, number of antibonding electron pairs in $O _{2}^{2-}$ molecular ion are four.