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JAMB Chemistry 1978 Question 11

Question 11

Air

When air, which contains the gases: oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are:

  1. A.nitrogen and carbondioxide
  2. B.the rare gases
  3. C.nitrogen and oxygen
  4. D.nitrogen and the rare gases
  5. E.nitrogen, carbondioxide and the rare gases.
Show the answer and explanation

Answer: D (nitrogen and the rare gases)

Explanation

Alkaline pyrogallol absorbs oxygen (and carbon dioxide), and quicklime absorbs carbon dioxide and water vapour. Only nitrogen and the rare gases pass through.