We need to determine the oxidation state of the metal element in each compound: A) Pb₃O₄ is a mixed oxide, often written as 2PbO·PbO₂. In PbO, O is -2, so Pb is +2. In PbO₂, O is -2 (total -4 for 2 O atoms), so Pb is +4. Lead has oxidation states +2 and +4 in Pb₃O₄. B) Fe₃O₄ is a mixed oxide, FeO·Fe₂O₃. In FeO, O is -2, so Fe is +2. In Fe₂O₃, O is -2 (total -6 for 3 O atoms), so 2 Fe atoms are +6, meaning each Fe is +3. Iron has oxidation states +2 and +3 in Fe₃O₄. C) Fe₂O₃: Assuming oxygen is -2, the total charge from 3 oxygen atoms is 3 (-2) = -6. For the compound to be neutral, the total charge from 2 iron atoms must be +6. Thus, the oxidation state of each Fe atom is +6 / 2 = +3. All iron atoms in Fe₂O₃ are in the +3 oxidation state. D) Mn₃O₄ is a mixed oxide, MnO·Mn₂O₃. In MnO, O is -2, so Mn is +2. In Mn₂O₃, O is -2 (total -6 for 3 O atoms), so 2 Mn atoms are +6, meaning each Mn is +3. Manganese has oxidation states +2 and +3 in Mn₃O₄.