Question:

Hydrogen peroxide acts both as an oxidizing and as a reducing agent, depending upon the nature of the reacting species. In which of the following cases H2O2 acts as a reducing agent in acid medium?

MnO₄⁻

Cr₂O₇²⁻

SO₄²⁻

The oxidation state of Mn in MnO₄⁻ is +7. H₂O₂ can only reduce Mn as it is in the maximum oxidation state in MnO₄⁻.