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When air which contains the gases Oxygen, nitrogen, carbo...

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

Correct answer is D

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