Phase is the state of matter at a given temperature and pressure. There are four possible phases for most substances: solid, liquid, gaseous and plasma. Phase is caused by the force of the attraction between a substance's particles (all substances are composed of molecules and atoms that are actually moving at all times). The phase of a substance changes when a certain amount of energy and/or pressure is applied to it. Take liquid water, for example. If you lower the temperature on liquid water, it freezes to become a solid: ice. Raising the temperature on ice will cause it to melt, returning it to its former phase. In its gaseous state, it is water vapor.
When you melt an ice cube, what is the new phase of the water?
A
plasma
B
liquid
C
gas
D
solid