Final answer:
The oxidation number of each oxygen atom in HOOH (hydrogen peroxide) is -1.
Step-by-step explanation:
The oxidation number of each oxygen atom in HOOH (hydrogen peroxide) is -1.
The oxidation numbers of hydrogen and oxygen in HOOH are determined by their electronegativity and the rules for assigning oxidation numbers. Oxygen is more electronegative than hydrogen, so oxygen is assigned an oxidation number of -1. Since HOOH is a neutral molecule, the sum of the oxidation numbers must be zero, so the oxidation number of each hydrogen atom is +1.
Therefore, the oxidation number of each oxygen atom in HOOH is -1.