$\mathrm{KO}_2$ exhibits paramagnetic behaviour. This is due to the paramagnetic nature of

$\mathrm{KO}_2$ exhibits paramagnetic behaviour. This is due to the paramagnetic nature of
  1. $\mathrm{KO}^{-}$
  2. $\mathrm{K}^{+}$
  3. $\mathrm{O}_2$
  4. $\mathrm{O}_2^{-}$

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

Asked in: AP EAMCET 2014

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