What is the percentage by mass of Fe in Fe₂O₃?
Answer and explanation
Correct answer: B. 70%
- Step 1: Mass of Fe in one formula unit = 112; formula mass = 160. Step 2. Percentage = 112 ÷ 160 × 100 = 70%. Answer: 70%. Why not the others: 30% is what you get if you give the percentage of the other element. 41.176% is what you get if you divide by the wrong total. 7% is what you get if you misplace the decimal point.
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