Which of the following is correctly based on molecular orbital theory for peroxide ion?

Options

A. Its bond order is two and it is paramagnetic.
B. Its bond order is two and it is diamagnetic.
C. Its bond order is one and it is diamagnetic.
D. Its bond order is one and it is paramagnetic.

Answer

C

Explanation

The peroxide ion `O_2^(2-)` has 18 electrons arranged in the following manner:
`sigma_(1s^2), sigma_(1s^2)^**, sigma_(2s^2), sigma_(2s^2)^**, sigma_(2p_z^2){:(pi_(2p_x^2),,),(pi_(2p_y^2),,):}]{:(pi_(2p_x^2)^**,),(pi_(2p_y^2)^**,):}]`
All the electrons are paired. Thus, `O_2^(2-)` ion is diamagnetic. The bond order may be calculated as (bonding-antibondig)/2, that is `(10-8)//2=1`.