Among KO2, AlO2-, BaO2 and NO2+, which of the following contain(s) an unpaired electron?A.NO2+ and BaO2B.KO2 and AlO2-C.KO2 onlyD.BaO2 only

To answer this question, we need to look at the electron configurations of the species mentioned.

1. KO2: Potassium superoxide (KO2) is a paramagnetic compound. It has an unpaired electron in its molecular orbital.

2. AlO2-: In Aluminium peroxide (AlO2-), Aluminium is in +3 oxidation state and each Oxygen is in -2 oxidation state. So, it does not have any unpaired electron.

3. BaO2: In Barium peroxide (BaO2), Barium is in +2 oxidation state and each Oxygen is in -1 oxidation state. So, it does not have any unpaired electron.

4. NO2+: Nitrogen dioxide cation (NO2+) is a diamagnetic species. It does not have any unpaired electron.

So, the correct answer is C. KO2 only.