In which state of matter are particles most closely packed?

In solids, particles are most closely packed because they are arranged in a fixed, orderly structure that minimizes the space between them. This tight packing allows solids to maintain a definite shape and volume. The strong intermolecular forces in solids hold the particles in place, preventing them from moving freely. As a result, solids are rigid and resist changes in shape.

In contrast, gases have particles that are much further apart, allowing them to fill any available space, which is why gases have neither a definite shape nor a definite volume. In liquids, although the particles are closer together than in gases, they are still not as tightly packed as in solids and can flow past one another. Plasma, often considered a fourth state of matter, consists of ionized gases with free-moving charged particles and is not characterized by closely packed particles. Therefore, the arrangement and behavior of particles in solids distinctly demonstrate that they are the state of matter with the most closely packed particles.