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JAMB Chemistry 2000 Question 4

Question 4

Gas Laws

50 cm3 of carbon (II) oxide was exploded with 150 cm3 of air containing 20% oxygen by volume. Which of the reactants was in excess?

  1. A.Carbon (II) oxide
  2. B.Carbon (IV) oxide
  3. C.Oxygen
  4. D.Nitrogen
Show the answer and explanation

Answer: C (Oxygen)

Explanation

2CO + O2 → 2CO2, so 50 cm3 of CO needs only 25 cm3 of O2. The air holds 20% × 150 = 30 cm3 of O2, so oxygen is in excess.