Final answer:
The temperature on the cooling curve of water decreases as heat energy is removed. The temperature drops until it reaches the boiling point of 100°C, at which point the water condenses into steam. The temperature then continues to decrease at a faster rate.
Step-by-step explanation:
When heat energy is removed from water over time, the temperature decreases on the cooling curve. Initially, the temperature drops until it reaches the boiling point of 100°C, at which point the water begins to condense into steam. The temperature remains constant at 100°C until all the water has been converted to steam. After that, the temperature begins to decrease again at a faster rate as the heat capacity of steam is less than that of ice or water.