Question

The number of anti-bonding electron pairs in $O_2^{2–}$ molecular ion on the basis of molecular orbital theory is:

• A. $3$
• B. $2$
• C. $5$
• D. $4$

Answer 1

The correct option is D $4$

$O_2^{2–}\left(18\right):\sigma 1s^2,{\sigma }^{\ast }1s^2,\sigma 2s^2,{\sigma }^{\ast }2s^2,\sigma 2p_z^2,\pi 2p_x^2,\pi 2p{y}^2,{\pi }^{\ast }2p_x^2,{\pi }^{\ast }2p_y^2$. Thus, the number of antibonding electrons in $O_2^{2–}$ ion is $8$ ($4$ pairs).