$\mathrm{O}_2, \mathrm{O}_2{ }^{-1}, \mathrm{NO}, \mathrm{CN}^{-1}, \mathrm{O}_2{ }^{2-}$
\(\mathrm{O}_2 \rightarrow\) 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 \(=0\)