Gas is easier to compress than a liquid or solid because the molecules in a gas are more spread out and have more space to move around. In a liquid, the molecules are closer together and have less space to move, so it is more difficult to compress. In a solid, the molecules are very close together and have no space to move, so it is almost impossible to compress.

Here is a more detailed explanation:

* Gas: The molecules in a gas are constantly moving and colliding with each other and the walls of their container. When a gas is compressed, the molecules have less space to move and collide with each other more often. This causes the pressure of the gas to increase.

* Liquid: The molecules in a liquid are also constantly moving, but they are closer together than the molecules in a gas. This means that they have less space to move and collide with each other more often. However, the molecules in a liquid are also attracted to each other by intermolecular forces. These forces help to hold the molecules together and make it more difficult to compress the liquid.

* Solid: The molecules in a solid are very close together and are held in place by strong intermolecular forces. This makes it very difficult to compress a solid.

The compressibility of a substance is a measure of how easily it can be compressed. The compressibility of a gas is much higher than the compressibility of a liquid or solid. This means that it is much easier to compress a gas than a liquid or solid.