Question

Which of the following molecule species has unpaired electron(s)?

• A. $N_2$
• B. $F_2$
• C. $O_2^{-}$
• D. $O_2^{2-}$

Answer 1

Answer: (C)

$O_2^{-}$

Electronic configuration are:

$N_2$: number of valence electrons = $2\times 5=10$

$F_2$: number of valence electrons = $2\times 7=14$

$O_2^{-}$: number of valence electrons = $2\times 6+1=13$

$O_2^{2-}$: number of valence electrons = $2\times 6+2=14$

Since $O_2^{-}$ has odd electrons therefore it will definitely have unpaired electron.

Hence, option $C$ is correct.