Final answer:
Particles exhibit no kinetic energy at absolute zero (0 K), the theoretical temperature where particle motion stops. However, due to quantum mechanics, even at 0 K, particles retain some minimal zero-point energy.
Step-by-step explanation:
Particles have no kinetic energy at the temperature known as absolute zero, where the motion of particles theoretically ceases. Absolute zero, 0 K on the Kelvin temperature scale, has never been achieved in the laboratory, although temperatures close to it have been reached. The Kelvin temperature of a substance is directly proportional to the average kinetic energy of its particles. For instance, hydrogen gas at 200 K has twice the average kinetic energy as that at 100 K. It is important to note that while particles would theoretically have no kinetic energy at absolute zero, quantum mechanics shows that particles still retain some zero-point energy even at 0 K, which means they are never completely at rest.