(c) Iron(II) gluconate, C12H22FeO14, is the active ingredient in some brands of iron supplements. A student carries out an experiment to determine the mass of iron(II) gluconate in one tablet of an iron supplement, using the method below. Stage 1 The student crushes two tablets and dissolves the powdered tablets in dilute sulfuric acid. Stage 2 The student makes up the solution from Stage 1 to 250.0 cm3 in a volumetric flask. Stage 3 The student then titrates 25.0 cm3 portions of the solution obtained in Stage 2 with 0.00200 mol dm-3 potassium manganate(VII). The student obtains a mean titre of 13.50 cm3. In this titration, 1 mol of manganate(VII) ions reacts with 5 mol of iron(II) ions. (i) Explain why the student used 0.00200 mol dm-3 potassium manganate(VII) solution for this titration, rather than the more usual concentration of 0.0200 mol dm-3 used in manganate(VII) titrations. (ii) Use the student's results to determine the mass, in mg, of iron(II) gluconate in one tablet. Give your answer to 3 significant figures. mass of iron(II) gluconate in one tablet = mg