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JEE Main20266 April 2026Morning ShiftChemistrySome Basic Concepts of ChemistryActual

An oxide of iron contains 69.9 % iron, its empirical formula, is: (Given: Molar mass of Fe and O are 56 and 16 g mol ⁻¹ respectively.)

Options

  1. AFeO
  2. BFe ₂ O ₃
  3. CFe ₃ O ₄
  4. DFeO ₃

Correct answer

B. Fe ₂ O ₃

Step-by-step solution

Mass percentage of Fe = 69.9 % Mass percentage of O = 100 % - 69.9 % = 30.1 % Number of moles of Fe = 69.9 56 = 1.248 Number of moles of O = 30.1 16 = 1.881 Molar ratio of Fe : O = 1.248 : 1.881 Dividing by the smallest value, the ratio is 1.248 1.248 : 1.881 1.248 = 1 : 1.5 Multiplying by 2 to get the simplest whole number ratio, we get 2 : 3 . The empirical formula is Fe ₂ O ₃ . Answer: Fe ₂ O ₃

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