a) melting (the passage from a crystal conformity to a liquid conformity because of more energy associated to its molecules)
b) boiling (the passage of a liquid to gas, usually by quick transition because of an increase of temperature)
c) freezing (when a liquid becomes solid by decrease of temperature, becoming a crystallised structure)
d) condensation (the passage from gas to liquid, it requires cooling the gas making the particles closer forming a more solid fluid then a gas - a liquid)
