Please help if you have time: determine the percentage by mass of Chromium in the ore. I got the moles cro4- then divided by 2 to get moles of fe(cro2)2 because it's 4:2 ratio. Mark scheme doesn't do

Please help if you have time: determine the percentage by mass of Chromium in the ore. I got the moles cro4- then divided by 2 to get moles of fe(cro2)2 because it's 4:2 ratio. Mark scheme doesn't do this. When j got 0.034 mol I divided by 2 but mark scheme keeps it as 0.034. When j got 0.017 I x it by 52 to get the mass of chromium which was wrong. Please explain why answer is 37-38 percent.