B
The arrangement of a substance's molecules changes when it changes phases, but its temperature remains constant. The substance absorbs thermal energy from its surroundings to undergo a phase shift if the new arrangement has a larger thermal energy content. The substance releases thermal energy onto its surroundings if the new arrangement contains less thermal energy.
A substance's physical characteristic is its latent heat of vaporization. Its definition is the amount of heat needed to transform a single mole of liquid at its boiling point at mean atmospheric pressure. It is stated in terms of kg/mol or kJ/kg. The energy causes a liquid substance to transition from a liquid form to a vaporous one.