Question

What happens to the temperature of a substance while it is changing state?

A. It varies randomly.
B. It decreases first and then remains constant.
C. It increases first and then decreases.
D. It remains constant.

Answer 1

The temperature of a substance remains constant during a phase change. As heat is added or subtracted during a transition between solid, liquid, or gas, temperature does not vary until the change is complete.

Step-by-step explanation:

The temperature of a substance remains constant while it is changing state. This process is known as an isothermal phase transition. Taking water as an example, when ice at 0°C absorbs heat, it will begin to melt, transitioning from a solid to a liquid, but the temperature will stay at 0°C until all the ice has melted. Only after the ice has completely melted will the temperature of the water begin to rise.