Question

$N_2$ and $O_2^{-}$ are converted into monoanions, $N_2^{-}$ and $O_2^{-}$ respectively. Which of the following statements are wrong?

• A. In $N_2$, $N-N$ bond weakens
• B. In $O_2^{-}$, $O-O$ bond order increases
• C. In $O_2^{-}$, $O-O$ bond order decreases
• D. $N_2^{-}$ becomes paramagnetic

Answer 1

Answer: (C)

In $O_2^{-}$, $O-O$ bond order decreases

Bond order=(number of bonding electrons) - (number of anti bonding electrons)/2.
Hence, bond order decreses with increase in electron in anti bonding molecular orbital.

Species	$N_2$	$O_2$	$N_2^{-}$	$O_2^{-}$
Bond order	$3$	$2$	$2.5$	$1.5$

The $O-O$ bond order in $O_2^{-}$ decreases.