Question

Among $K{O}_2$, $Al{O}_2^{-}$ , $Ba{O}_2$ and $N{O}_2^{+}$, unpaired electron is present in

• A. $N{O}_2^{+}$ and $Ba{O}_2$
• B. $K{O}_2$, and $Al{O}_2^{-}$
• C. Only $K{O}_2$
• D. Only $Ba{O}_2$

Answer 1

Answer: (C)

Molecular orbital electronic configuration are

Has one unpaired electron in $\stackrel{\ast }{\pi }2p$ orbital.
$Al{O}_2^{-}$has both oxygen in $O^{2-}$ state, therefore, no unpaired electron is present. $Ba{O}_2\left(O_2^{2-}\right)$

Has no unpaired electron.
$N{O}_2^{+}$has $\left[O=\stackrel{+}{N}=O\right]$ bonding, hence no unpaired electron.