Energy needs to be put in to break intermolecular bonds.
When a liquid is heated, the energy makes the particles move faster.
When enough of the particles have the energy to break their bonds to each other, gas bubbles form in the liquid (this is boiling).
When a solid is heated, the particles vibrate faster until the forces between them are broken and they start to move about as a liquid (this is melting).
When a substance is…