Among ` KO_2 , AlO_(2)^(-) BaO_2` and `NO_2^+` unpaired electron is present in :

Options

A. `NO_(2)^(+) and BaO_(2)`
B. `KO_(2) and AlOI_(2)^(-)`
C. only `KO_(2)`
D. only `BaO_(2)`

Answer

C

Explanation

Molecular orbital electronic configuration are
`KO_(2)(O_(2)^(-)):sigma1s^(2)overset(***)sigma1s^(2)sigma2s^(2)overset(***)sigma2s^(2) sigma2p_(x)^(2)|(pi2p_(y)^(2)),(pi2p_(z)^(2))||(overset(***)pi2p_(y)^(2)),(overset(***)pi2p_(z)^(1))|overset(**)sigma2p_(x)^(0)`
Has one unpaired electron in `overset(***)pi 2p` orbital.
`AlO_(2)^(-)` has both oxygen in `O^(2-)` state, therefore, no unpaired electron is present.
`BaO_(2) (O_(2)^(2-))`
`sigma1s^(2)overset(***)sigma1s^(2)sigma2s^(2)overset(***)sigma2s^(2) sigma2p_(x)^(2)|(pi2p_(y)^(2)),(pi2p_(z)^(2))||(overset(***)pi2p_(y)^(2)),(overset(***)pi2p_(z)^(2))|overset(**)sigma2p_(x)^(0)`
Has no unpaired electron. `" " NO_(2)^(+)` has `[O = overset(+)N=O]` binding, hence no unpaired electron.