Final answer:
To calculate the mass percentage of iron in Fe₂O3, divide the molar mass of iron by the molar mass of Fe₂O3 and multiply by 100%. The correct answer is B. 35.91%.
Step-by-step explanation:
To calculate the mass percentage of iron in the compound Fe₂O3, we need to first determine the molar mass of iron and the molar mass of Fe₂O3. Iron (Fe) has a molar mass of 55.8 g/mol and Fe₂O3 has a molar mass of 159.7 g/mol.
To calculate the mass percentage of iron, we divide the molar mass of iron by the molar mass of Fe₂O3 and multiply by 100%:
Mass percentage of iron = (55.8 g/mol / 159.7 g/mol) × 100% = 34.95%
Therefore, option B. 35.91% is the correct answer.