Answer:
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Experiment : 3 Marks
Diagram : 2 Marks
Take a candle and fix it at the center of a glass container. Add some quantity of water in the glass container. Now place an empty glass jar over it. Above the water surface, mark five lines at equal distances as depicted in the diagram below.
Carefully light the candle and wait for a few seconds. The flame will be extinguished due to the absence of oxygen. We can observe that the water level in the glass jar is 1/5 of the volume of air present in the glass jar. The above experiment proves that one part of the air present in the glass jar supports the combustion process, i.e., oxygen. Hence, 1/5^th of the volume of air is oxygen. Thus, we can conclude that air contains nitrogen and oxygen in the ratio 4:1.