Answer:
We can change the physical state of a substance by heating or cooling it. For example, liquid water can be heated to convert it into the gaseous form i.e steam. Steam can be cooled or condensed to convert it into liquid water.
Liquid water can be cooled to convert it into the solid physical state which will be ice. Ice can be heated to convert it into liquid again. Hence, we can change the physical states by heating or cooling a substance.