The chain goes:
gas ---> liquid ---> solid
Whenever you move left on the chain, heat added. Whenever you move right, heat is removed.
1. Solid to liquid; heat added
Liquid to solid; heat removed
Liquid to gas; heat added
Gas to liquid; heat removed
2. Solid to liquid; melting
3. a) Liquid to gas; vaporization
b) Liquid to solid; freezing
c) Gas to liquid; condensation
d) Solid to gas; sublimation
4. Water gets into the air by evaporation. When water is in the air, it is in a gas phase.
5. That one is on you.
