138. Solving a chemistry problem

84. How many percent of iron is contained in 2.00 g of siderite if, after dissolving in acid, the solution was diluted in a volumetric flask to 200 cm3, and 22.50 cm3 of KMnO4 solution with C (1 / 5KMnO4 ) = 0.1000 mol / dm3. F = 1.922