$\mathrm{O}_2, \mathrm{O}_2{ }^{-1}, \mathrm{NO}, \mathrm{CN}^{-1}, \mathrm{O}_2{ }^{2-}$
$\mathrm{O}_2 \rightarrow$ no. of unpaired electrons $=2$
$\mathrm{O}_2^{-} \rightarrow$ no. of unpaired electron $=1$
NO $\rightarrow$ no. of unparred electron $=1$
$\mathrm{CN}^{-} \rightarrow$ no. of unparred electron $=0$
$\mathrm{O}_2^{2-} \rightarrow$ no. of unpaired electron $=0$
$(i)\, KCl$ અથવા $MgO$ $(ii) \,LiF$ અથવા $LiBr$ $(iii)\, Mg_3N_2$ અથવા $NaCl$