Final answer:
Gases are more compressible than liquids or solids due to the large separation between gas molecules and the weak intermolecular forces, which allow them to be easily pushed closer together when pressure is applied.
Step-by-step explanation:
The kinetic theory explains why gases are more easily compressed than liquids or solids. The key is in the large separation between gas molecules, which are spaced further apart compared to their sizes, allowing them to be pushed closer with relative ease. In contrast, atoms and molecules in liquids and solids are much closer, with attractive forces between them playing a significant role, making these states of matter less compressible. The compressibility of gases can be visually observed when pressure is applied, for instance, using a bicycle pump to move air into a tire, compressing the same number of gas molecules into a smaller volume.
Additionally, gases expand and contract very rapidly with temperature changes due to the large coefficients of volume expansion. The fast motion of the gas molecules means they occupy all accessible space and expand swiftly, in contrast to liquids and solids where the expansion rate is more variable and less significant because of the closer particle proximity and intermolecular forces.