A student heats a liquid on a burner. What happens to the portion of liquid that first begins to warm? It loses energy.
It becomes less dense.
It sinks downward.
Its molecules get closer together.

I believe it becomes less dense, bc when you heat something it’s molecules spread further apart.

Yes it becomes less dense because when the water molecules are hot it tends to go around more faster but if it was cold it would stay still. Just like us humans would do.

The chemical bubbles

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water