If someone holds a piece of gallium metal and it melts at body temperature, the change that occurs is a physical change.
A physical change involves changes in the state of matter (such as melting, freezing, or boiling) without altering the chemical composition of the substance. When gallium melts, it transitions from a solid to a liquid while retaining its chemical properties; it remains gallium (Ga).
In contrast, a chemical change would involve a transformation that results in the formation of new substances with different properties, such as when a chemical reaction occurs and molecular bonds are broken and formed. Since melting does not produce a new substance, but merely changes the state of gallium, it is classified as a physical change.