Gases exhibit no shape and
volume because the particles can move freely from one other. Their collisions
are rare due to the distance between them. The kinetic energy of the molecules
is high because there is room for movement. And because the particles are far
away from each other, it can be compressed easily. When you compressed a gas,
you are decreasing the distance between the particles. Bringing the particles
closer makes room for more interaction because repulsive forces dominate. The gas
then will turn into liquid.
