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;

  • A nitrogen and carbondioxide
  • B the rare gases
  • C nitrogen and oxygen
  • D nitrogen and the rare gases
jamb 2018chemistry

The correct answer is D. nitrogen and the rare gases

The quick-lime is a drying agent that can dry most gases except ammonia. Hence it removes the water vapour. Quick-lime which is calcium oxide reacts with the carbon dioxide forming calcium carbonate. Hence carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases

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