Which change results in a release of energy?
1. the melting of h₂o(s)
2. the boiling of water(l)
3. the evaporation of h₂0 (l)
4. the condensation of h₂0(g)

The answer to this question would be: 
4. The condensation of H₂0(G)
The reaction that release heat/energy is called exothermic. Melting H2O mean you change the form from solid(ice) into liquid(water). To melt ice you need to heat it, that makes it endothermic since it absorbs heat, not produce it. 
Boiling water is the same, you need heat to do that. Evaporating H2O also need heat like boiling. 
In condensation, the vapor(gas) becomes liquid. It was the opposite of evaporating. In this reaction, you need to cool the vapor. Cooling the vapor is same as the vapor release energy to surrounding, which makes it exothermic.

Neither model is able to show the reactivity of potassium.

I'm sorry but i'm only grade