Final answer:
The motion of molecules is closely related to the state of matter. In a solid, molecules vibrate in place. In a liquid, molecules can move around and slide past each other. In a gas, molecules move freely and collide randomly with each other.
Step-by-step explanation:
Matter most commonly exists as a solid, liquid, or gas. Solids have a definite shape and volume, liquids have a definite volume but their shape changes depending on the container, and gases have neither a definite shape nor a specific volume. The motion of molecules is closely related to the state of matter. In a solid, molecules vibrate in place. In a liquid, molecules can move around and slide past each other. In a gas, molecules move freely and collide randomly with each other.