Final answer:
The phase of matter with the most kinetic energy is gas. Molecules in a gaseous state can move freely and have the highest energy compared to molecules in liquid and solid states. Plasma is more energetic than gas, but it was not an option in the question.
Step-by-step explanation:
The phase of matter with the most kinetic energy is gas. In the gaseous state, molecules have enough energy to move freely and overcome the intermolecular forces that are much stronger in liquids and solids. Among the options provided, which include colloid, gas, liquid, and solid, gas molecules possess the highest kinetic energy.
Liquids are in a state where the atoms or molecules have more energy than in the solid phase but less than in the gas phase. Particles are still held together by their mutual attraction but can slide smoothly past one another and change neighbors. Solids are the least energetic state, where atoms vibrate but do not change position with neighboring particles due to strong intermolecular forces. Plasma is another state of matter that is even more energetic than gas, but it is not one of the options provided in the original question.
To understand which phases of matter allow molecules to change their positions, we look at their molecular behavior. Solids resist shearing forces, and their molecules do not change positions easily. By contrast, both liquids and gases, which are fluids, allow their molecules to move and change neighbors. This is a key characteristic that separates them from solids in terms of molecular motion capability.