KO2 is rare and is called potassium superoxide. It consists of K+ ion and O^2- ion. In this case, the oxidation number of O would be 1-. If, however, you meant to ask about K2O (potassium oxide), then the oxidation number of O would be 2-
Oxidation number of Se is +6. Oxidation number of O is -2.
The oxidation number is + for C and -2 for O.
O = -2 oxidation state H = +1 oxidation state
Each of the hydrogen atoms in H2 has an oxidation number of 0.
+2 for Mg -2 for O
+3
Oxidation state of K in KO2 is - 0.5 because its structure is K-O=O .
The principal oxidation state of NA in NA2O2 and K in KO2 is +1
Ru has oxidation number +8, O has oxidation number of -2
The overall oxidation number is -2 so the average oxidation number of O is -1.
Oxidation number of chlorine is +7. oxidation number of O is -2.
The oxidation number for H is +1, and the oxidation number for O is -1.
Oxidation number of Si is +4.Oxidation number of O is -2.
Oxidation number of Nb is +4. Oxidation number of O is -2.
Oxidation number of C is +3. Oxidation number of O is -2.
Oxidation number of N is +1. Oxidation number of O is -2.
Oxidation number of Ti is +2. Oxidation number of O is -2.