Number of paramagnetic oxides among the following given oxides is ____________.

Li₂O, CaO, Na₂O₂, KO₂, MgO and K₂O

Li₂O $\Rightarrow$ 2Li⁺ O^2$-$<br><br>CaO $\Rightarrow$ Ca²⁺ O^2$-$<br><br>Na₂O₂ $\Rightarrow$ 2Na⁺ O$_2^{2 - }$<br><br>KO₂ $\Rightarrow$ O$_2^{- }$<br><br>MgO $\Rightarrow$ Mg²⁺ O^2$-$<br><br>K₂O $\Rightarrow$ 2K⁺ O^2$-$<br><br>O^2$-$ $\Rightarrow$ Complete octet, diamagnetic<br><br>$O_2^{2−}$ has 18 electrons. <br><br>Moleculer orbital configuration of $O_2^{2−}$ is <br><br>$${\sigma _{1{s^2}}}\,\sigma _{1{s^2}}^ * \,{\sigma _{2{s^2}}}\,\sigma _{2{s^2}}^ * \,{\sigma _{2p_z^2}}\,{\pi _{2p_x^2}}\, = \,{\pi _{2p_y^2}}\,\pi _{2p_x^2}^ * \, = \,\pi _{2p_y^2}^ * $$ <br><br>Here is no unpaired electron so it is diamagnetic. <br><br>$O_2^{−}$ has 17 electrons. <br><br>Moleculer orbital configuration of $O_2^{−}$ is <br><br>$${\sigma _{1{s^2}}}\,\sigma _{1{s^2}}^ * \,{\sigma _{2{s^2}}}\,\sigma _{2{s^2}}^ * \,{\sigma _{2p_z^2}}\,{\pi _{2p_x^2}}\, = \,{\pi _{2p_y^2}}\,\pi _{2p_x^2}^ * \, = \,\pi _{2p_y^1}^ * $$ <br><br>Here is 1 unpaired electron so it is paramagnetic.