Answer:
Both “a crayon melting in the sun” and “mixing sand and gravel” involve physical changes.
In the case of a crayon melting in the sun, the heat from the sun causes the wax in the crayon to change from a solid state to a liquid state. This is a physical change because it affects the state of the matter (from solid to liquid) but not its chemical composition.
Similarly, when you mix sand and gravel, you’re not changing the chemical composition of either the sand or the gravel. You’re simply rearranging the particles to create a mixture. This is also a physical change.
So, the commonality between these two scenarios is that they both involve physical changes, not chemical changes. Physical changes are usually reversible and do not involve a change in the substance’s chemical composition.