The state of matter that has the most kinetic energy is the gas state. In the gas state, particles are far apart and move freely at high speeds. This high-speed movement results in the highest kinetic energy among the three primary states of matter: solid, liquid, and gas.
In solids, particles are tightly packed and vibrate in place, which means they have the least kinetic energy. In liquids, particles are less tightly packed than in solids and can move past each other, giving them more kinetic energy than solids but less than gases.
Therefore, gases have the most kinetic energy because their particles move the fastest and are the least constrained by intermolecular forces.