Question

Which of the following ions does not have a bond order of $2.5$?

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

Answer 1

The correct option is A $O_2^{-}$

For $O_2^{-}$

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{z}^{2}2p{x}^{2}2p{y}^2\ast 2p{x}^2\ast 2p{y}^1$

Bond Order = $\frac{6-3}{2}=1.5$

For $N_2^{-}$

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{x}^{2}2p{y}^{2}2p{z}^2\ast 2p{x}^1$

Bond Order = $\frac{6-1}{2}=2.5$

For $O_2^{+}$

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{z}^{2}2p{x}^{2}2p{y}^2\ast 2p{x}^1\ast 2p{y}^0$

Bond Order = $\frac{6-1}{2}$ = 2.5

For $N_2^{+}$

$1s^2\ast 1s^{2}2s^2\ast 2s^{2}2p{x}^{2}2p{y}^{2}2p{z}^1$

Bond Order = $\frac{5-0}{2}=2.5$

Bond Order of $O_2^{+},N_2^{-}$ and $N_2^{+}$ = $2.5$.

Hence, the correct option is 'A'