In this question, we are looking for a compound that does not exhibit a different oxidation number of the same element.

Option 1: Pb2O4

This compound contains lead (Pb) and oxygen (O). In Pb2O4, lead has an oxidation number of +4, which is different from other compounds where lead can have different oxidation numbers.

Option 2: Fe3O4

This compound contains iron (Fe) and oxygen (O). In Fe3O4, iron has two different oxidation numbers: +2 and +3. Therefore, this compound exhibits a different oxidation number of the same element.

Option 3: Fe2O3

This compound also contains iron (Fe) and oxygen (O). In Fe2O3, iron has an oxidation number of +3, which is consistent across all compounds containing iron and oxygen.

Option 4: Mn3O4

This compound contains manganese (Mn) and oxygen (O). In Mn3O4, manganese has two different oxidation numbers: +2 and +3. Therefore, this compound exhibits a different oxidation number of the same element.

Based on this analysis, option 2 is correct because Fe3O4 is the only compound that