Question

How is energy related to the change of state represented by the model?

Atoms gain energy as a solid changes to a gas.
Atoms gain energy as a liquid changes to a gas.
Atoms lose energy as a solid changes to a gas.
Atoms lose energy as a liquid changes to a gas.

Answer 1

Atoms gain energy when a substance changes to a higher‑energy state (solid → liquid → gas). So, for example, atoms gain energy as a liquid changes to a gas (and likewise if a solid goes directly to a gas — sublimation — energy must be added).