O Levels Chemistry (5070)•5070/12/M/J/22
Explanation
Oxygen Consumption in Candle Burning Experiment Steps:
- Candle flame consumes oxygen from the air inside the container to burn.
- As oxygen (about 21% of air) is used up, the total gas volume decreases, lowering pressure inside.
- Atmospheric pressure pushes water up from the surrounding container to equalize pressure.
- Water level rises by approximately one-fifth of the air volume, matching oxygen depletion.
Why C is correct:
- Diagram C shows water rising to about 20% of the container height, aligning with the law of partial pressures where oxygen consumption reduces internal pressure by 21%.
Why the others are wrong:
- A shows no water rise, ignoring oxygen depletion and pressure change.
- B shows water filling over half, exaggerating the oxygen volume beyond 21%.
- D shows minimal rise, underestimating the oxygen consumed.
Final answer: C
Topic: Redox
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