Final answer:
The temperature does not initially increase as energy is added after ice begins to melt because the added energy is used to break the hydrogen bonds within water molecules. Temperature only increases after the ice has completely melted.
Step-by-step explanation:
During the melting process of ice, the added energy is used to break the hydrogen bonds within water molecules, not to increase the temperature. The temperature remains constant because all of the energy is going into the phase change from solid to liquid. This is because energy is required to break the attractive forces between the water molecules in the solid state so that they can move around freely in the liquid state. Once all the ice has melted, further addition of energy will cause the temperature to increase.