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JAMB Chemistry 1980 Question 12

Question 12

Gas Laws

500cm3 oxygen was collected over water at 30°C and 752 mmHg pressure. What is the volume of dry oxygen at S.T.P? (Vapour pressure of water at 30°C = 32 mmHg).

  1. A.475 cm3.
  2. B.415cm3
  3. C.586 cm3
  4. D.500 cm3
  5. E.427 cm3.
Show the answer and explanation

Answer: E (427 cm3.)

Explanation

Pressure of dry oxygen = 752 − 32 = 720 mmHg. V = 500 × (720/760) × (273/303) ≈ 427 cm3.