Oxygen Consumption in Candle Burning Experiment

Steps:

• Candle flame reacts with oxygen from air inside the container to produce CO2 and H2O.
• Oxygen (about 21% of initial air volume) is consumed, reducing total gas volume.
• Atmospheric pressure pushes water up to equalize pressure inside the container.
• Final water level rises by approximately 21% of initial air volume above the candle.

Why C is correct:

• Diagram C shows water level rising by roughly one-fifth of the air space, matching the oxygen volume fraction per the composition of air.

Why the others are wrong:

• A shows no water level change, ignoring gas volume reduction.
• B shows water fully filling the container, overestimating oxygen consumption.
• D shows minimal rise, underestimating the oxygen proportion in air.

Final answer: C