KO₂ is paramagnetic  because of presence of 

two unpaired electrons  2${\mathrm{\pi }}^{*}$orbital of ${\mathrm{O}}_2^{-}$

one unpaired electron in 2${\mathrm{\pi }}^{*}$orbital of K⁺

one unpaired electron in 2$\mathrm{\pi }$ orbital of ${\mathrm{O}}_2^{-}$

one unpaired electron in 2${\mathrm{\pi }}^{*}$ orbital of ${\mathrm{O}}_2^{-}$