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JAMB Chemistry 1985 Question 7

Question 7

Mole Concept and Stoichiometry

Given that the molecular mass of iron is 56 and that of oxygen is 16, how many moles of iron (III) oxide will be contained in 1 kg of the compound?

  1. A.25.0 moles
  2. B.12.5 moles
  3. C.6.25 moles
  4. D.3.125 moles
  5. E.0.625 moles
Show the answer and explanation

Answer: C (6.25 moles)

Explanation

Molar mass of Fe2O3 = 2 × 56 + 3 × 16 = 160 g. Moles in 1000 g = 1000/160 = 6.25.