They vibrate in place within a fixed volume. They move around freely within a fixed volume. They vibrate in place and take the shape of a container. They move around freely and take the shape of a container.
I gave my students this multiple choice question: Which statement best describes the motion of the molecules of a solid object?

Only one answer is correct among these 4 choices:
- They vibrate in place within a fixed volume.
- They move around freely within a fixed volume.
- They vibrate in place and take the shape of a container.
- They move around freely and take the shape of a container.

Could you tell me which one is correct?

They vibrate in place within a fixed volume.