Answer:
the space between particles
increases the particles move faster
Step-by-step explanation:
Melting and boiling points are phase changes as a result of heating of substances.
When a substance is heated, the heat content of its matter increases. In this regard, temperature rises and reaches a point where it steadies. A phase change occurs here. Most times, heat gives more energy to particles that makes up a substance. This makes intermolecular vibrations to increase and as it reaches the boiling and melting point, molecules can break free and be independent. Sometimes they flow freely.
This simply implies that there is more intermolecular space for them to move and the particles are able to move more freely.