How do molecules move in gas

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

What energy conversion occurs when a sling shot is used to shoot a rock across the room? (2 points) question 2 options: 1) stored mechanical energy is converted to mechanical energy. 2) stored mechanical energy is converted to radiant energy. 3) gravitational energy is converted to radiant energy. 4) gravitational energy is converted to mechanical energy.

Is the flow of energy during vaporizing more like the flow during melting or during freezing