When liquid water is converted to water vapor at constant mass, what happens to its volume and mass?

• A. The volume decreases, but the mass remains the same.
• B. The volume increases, but the mass remains the same.
• C. Both the volume and mass increase.
• D. Both the volume and mass decrease.

Answer: (B)

Verified step by step guidance

1. Identify the physical process: liquid water is converted to water vapor, which is a phase change from liquid to gas.
2. Recall that during a phase change at constant mass, the amount of substance (mass) does not change because no water is added or removed.
3. Understand that the volume of a substance changes significantly when it changes phase from liquid to gas; gases occupy much more volume than liquids.
4. Therefore, the volume increases because water vapor takes up more space than liquid water at the same mass.
5. Conclude that the mass remains constant while the volume increases during the conversion from liquid water to water vapor.