Question

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

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

Answer 1

Answer: (C)

$O_2^-$

Answer 2

$O_2^-$ has odd number (17) of electrons, therefore it must
contain at least one unpaired electron.