Stability of the species `Li_(2), Li_(2)^(-)` and `Li_(2)^(+)` increases in the order of

Options

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

Answer

C

Explanation

Stability depends upon bond order.
`Li_(2):KK(sigma2s)^(2):" Bond order "=1`
`Li_(2)^(+):KK(sigma2s)^(1):"Bond order"=(1)/(2)`
`Li_(2)^(-):KK(sigma2s)^(2)(sigma^(**)2s)^(1):"Bond order"=(1)/(2)`
`Li_(2)^(+)` is more stable than `Li_(2)^(-)` because it has less number of antibonding electrons. Hence,
`Li_(2)^(-)ltLi_(2)^(+)ltLi_(2)`