In `O_2^-, O_2 ` and `O_2^(-2)` molecular species, the total number of antibonding electrons respectively are

Answer

21

Explanation

Molecular orbital electroic configuration of these species are:
`O_(2)^(-)(17e^(-)), sigma 1s^(2), sigma^(*) 1s^(2), sigma 2s^(2), sigma^(*)2s^(2), sigma2p_(z)^(2), pi 2p_(x)^(2)= pi 2p_(y)^(2), pi^(*)2p_(x)^(2)=pi^(*)2p_(y)^(1)`
`O_(2)(16e^(-)): sigma 1s^(2), sigma^(*)1s^(2), sigma2s^(2), sigma^(*)2s^(2), sigma2p_(z)^(2), pi2p_(x)^(2) = pi2p_(y)^(2), pi^(*)2p_(x)^(1) = pi^(*)2p_(y)^(1)`
`O_(2)^^(2-)(18e^(-)), sigma1s^(2), sigma^(*)1s^(2), sigma2s^(2), sigma^(*)2s^(2), sigma2p_(z)^(2), pi2p_(x)^(2), pi2p_(y)^(2), pi^(*)2p_(x)^(2) = pi^(*)2p_(y)^(2)`
Hence, number of antibonding electrons are 7,6 and 8 respectively.