Which one of the following species will have maximum bond dissociation energy?

Options

A. `C_2`
B. `C_2^(+)`
C. `C_2^(-)`
D. `C_2^(2-)`

Answer

D

Explanation

`C_2` (8 electrons), KK `(sigma2s)^2 (sigma^("*") 2s)^2 (pi^("*")2p_x)^2 (pi2p_y)^2` Bond order =`(6-2)//2 = 2`
`C_2^(+)` (7 electrons), Bond order = `(5-2)//2 = 1 1/2`
`C_2^(-)` (9 electrons), KK `(sigma2s)^2 (sigma^("*") 2s)^2 (pi2p_x)^2 (sigma2p_y)^(1)` Bond order = `(7-2)//2 = 2 1/2`
`C_2^(2-)` (10 electrons), Bond order = `(8-2)//2`=3
Larger the bond order, larger the dissociation energy.