Which state of matter undergoes changes in volume most easily?
The gaseous state of matter undergoes changes in volume most easily.
What distinguishes a gas from liquids and solids is the vast separation of the individual gas particles.
This separation usually makes a colorless gas invisible to the human observer.
Since the molecules of a gas are so far apart, we can force them closer together by decreasing the volume.
We can also pull them away from each other by increasing the volume.