In FeC₂O₄, Fe²⁺ → Fe³⁺ (1 e⁻ loss) and C₂O₄²⁻ → 2CO₂ (2 e⁻ loss), for a total of 3 electrons lost. In MnO₄⁻ → Mn²⁺, 5 electrons are gained. To balance electrons, 5 moles of FeC₂O₄ react with 3 moles of MnO₄⁻. Therefore, 1 mole of FeC₂O₄ reacts with 3/5 = 0.6 moles of MnO₄⁻.