Among the choices given, the correct answer is the first option. Substance X most likely is a crystal, and substance Y most likely is a liquid. Substance X having a fixed volume describes a crystal because crystals occupy a certain volume. Substance Y is a liquid because liquids can still be compressed further in order to attain a more packed <span>structure.</span>
A unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12. It is equal to approximately 1.66 x 10-27<span> kg.</span>
D will because water just turns from liquid to a gas by adding heat. That is a physical change. The other equations are chemical changes.