Which of the following has least bond energy ?

Options

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

Answer

D

Explanation

(a ) ` N_2^ ( 2-) = KK' sigma2 s^2, overset (**)sigma 2 s ^2 , sigma 2p_z^ 2 , pi 2p_x^ 2 ~~pi 2p_y^ 2, overset(**)pi2p_x^2 `
` therefore ` Bond order = ` ( N_ b - N _a ) /(2 ) `
`= ( 8 - 4 ) /( 2 ) = 2 `
(b) ` N_2^ ( -) = KK' sigma2 s^2, overset (**)sigma 2 s ^2 , sigma 2p_z^ 2 , pi 2p_x^ 2 ~~pi 2p_y^ 2, overset(**)pi2p_x^1 `
Bond order ` = ( 8-3)/(2) =2.5 `
(c) `N _2 ^+ = KK' sigma 2s^ 2 overset (**)sigma2s^ 2 , pi 2p_x^ 2 ~~ pi 2p _y^ 2 ,sigma2p_x^1 `
Bond order = ` (7-2)/( 2 ) = 2.5 `
(d) `N_2 = KK' sigma 2s^ 2, overset(**)sigma 2s^2, pi 2p_x^2 ~~ pi 2p_y^2, sigma 2p_z^2 `
Bond order `= ( 8-2)/(2)= 3 `
` because ` Bond energy ` prop ( 1 ) /("Bond order") `
` therefore N _ 2 ` has least bond energy.