The mass of the zinc atoms decreased. The zinc atoms lost their relative fixed position. The zinc atoms were changed into atoms of another element. The size of the zinc atoms decreased.
I gave my students this multiple choice question: A student observes zinc turning from a solid to a liquid in a laboratory investigation. Which statement describes the change in zinc atoms while melting?

Only one answer is correct among these 4 choices:
- The mass of the zinc atoms decreased.
- The zinc atoms lost their relative fixed position.
- The zinc atoms were changed into atoms of another element.
- The size of the zinc atoms decreased.

Could you tell me which one is correct?

The zinc atoms lost their relative fixed position.