Q28 / 160 · TS EAMCET 2014 · Chemistry
$\mathrm{KO}_2$ exhibits paramagnetic behaviour. This is due to the paramagnetic nature of
- A$\mathrm{KO}^{-}$
- B$\mathrm{K}^{+}$
- C$\mathrm{O}_2$
- Correct answerD$\mathrm{O}_2^{-}$
Solution
In $\mathrm{KO}_2$, oxygen exists as $\mathrm{O}_2^{-}$ion. Its molecular orbital electronic configuration is as follows
$$
\begin{aligned}
\mathrm{O}_2^{-} & =\sigma 1 s^2, \tilde{\sigma} 1 s^2, \sigma 2 s^2, \dot{\sigma} 2 s^2, \sigma 2 P_z^2 \\
\pi 2 p_x^2 & \approx \pi^2 p_y^2, \pi 2 p^2{ }_x \approx \tilde{\pi} 2 p^{-1} y
\end{aligned}
$$
Due to presence of 1 unpaired electron in anti bonding molecular orbital, it is paramagnetic inbehaviour.
Hence, the correct answer is option: 'D'.