Final answer:
The percentage of oxygen in the air would remain unchanged if a sample of air in a closed container was heated.
Step-by-step explanation:
The percentage of oxygen in the air would remain unchanged if a sample of air in a closed container was heated. This is because the composition of air remains constant even when it is heated. Air is composed of various gases, including nitrogen, oxygen, carbon dioxide, and others. When air is heated, the gases in the air expand, but their relative concentrations remain the same.
For example, if a closed container initially contains 20% oxygen and 80% nitrogen, heating the container will cause the gases to expand, but the percentage of oxygen will still be 20% and the percentage of nitrogen will still be 80%. The increase in volume due to heating does not affect the relative concentrations of the gases.
Therefore, the percentage of oxygen in the air remains the same when a sample of air in a closed container is heated.