A 1.362 g sample of an iron ore that contained Fe3O4 was dissolved in acid and all of the iron was reduced to Fe2+. The solution was then acidified with H2SO4 and titrated with 39.42 mL of 0.0281 M KMnO4, which oxidized the iron to Fe3+. The net ionic equation for the reaction is 5Fe2+ + MnO4- + 8H+ h 5Fe3+ + Mn2+ + 4H2O (a) What was the percentage by mass of iron in the ore? (b) What was the percentage by mass of Fe3O4 in the ore?