Which of the following best explains why it can be difficult to accurately measure the volume of a gas in a laboratory setting?

• A. Gases expand to fill their container, making their volume dependent on the container's size and shape.
• B. Gases are always heavier than liquids, making them difficult to contain.
• C. Gases do not exert any pressure, so their volume cannot be measured.
• D. Gases have a fixed volume that does not change with temperature or pressure.

Answer: (A)

Verified step by step guidance

1. Understand the nature of gases: Gases do not have a fixed shape or volume; instead, they expand to fill the entire volume of their container.
2. Recall that the volume of a gas depends on the size and shape of the container because gas particles move freely and spread out evenly.
3. Recognize that this property makes it challenging to measure the volume of a gas directly, as the gas will always conform to the container's dimensions.
4. Eliminate incorrect options by applying basic gas properties: gases are not necessarily heavier than liquids, they do exert pressure, and their volume changes with temperature and pressure.
5. Conclude that the best explanation is that gases expand to fill their container, making their volume dependent on the container's size and shape.