A gas of N molecules is enclosed in a container. If the container volume is suddenly doubled at constant temperature (free expansion, no heat exchange), the rms speed of the molecules:

Answer: Remains the same since temperature is unchanged.

• A Doubles, as if the rms speed scaled directly with the container volume
• B Halves, as if the rms speed scaled inversely with the container volume
• C Remains the same since temperature is unchanged
• D Becomes zero, as if all molecular motion stopped after expansion