Which of the following option w.r.t. increasing bond order is correct ?

Options

A. `NO lt C_(2) lt O_(2)^(-) lt He^(+)`
B. `C_(2) lt NO lt He^(+) lt O_(2)^(+)`
C. `He^(+) lt O_(2)^(+) lt NO lt C_(2)`
D. `He^(+) lt O_(2)^(+) lt C_(2) lt NO`

Answer

D

Explanation

Bond order of the molecules :
`O_(2) : "KK"(sigma2s)^(@) (sigma^(**)2s)^(2) (sigma2p_(x))^(2)(pi2p_(y))^(2)(pi2p_(2))^(2)(pi^(**)2p_(y))^(2) (pi2P_(z))^(1)`
Bond order of `O_(2)^(-)=(1)/(2)(8-5)=1.5 `
`He_(2)^(+) : (sigma^(**)2s)^(1)`
Bond order of `He_(2)^(+)=(1)/(2)(2-1)=0.5`
`C_(2): "KK" (sigma2s)^(2) (sigma^(**)2s)^(2) (sigma2P_(x))^(2)(pi2P_(y))^(1)(pi2p_(z))^(1)`
Bond order `=1/2 (6-2)=2.0`
`NO : "KK" (sigma2s)^(2) (sigma^(**)2s)^(2)(sigma2p_(x))^(2) (pi^(2)p_(y))^(2)(pi^(2)p_(z))^(2) (sigma^(**)2p_(x))^(1)`
Bond order `=1/2 (8-3) =2.5`