Why are gases generally less dense than solids?

Gases are generally less dense than solids primarily because they consist of particles that are far apart from each other and move rapidly. In a gas, the particles are in constant motion and have significant space between them, which is a result of the weak intermolecular forces that allow them to move freely and occupy a larger volume compared to solids.

In solids, particles are closely packed together in a fixed structure, which leads to a high density. The forces between solid particles are much stronger, restricting their movement and keeping them in a tightly bound arrangement. In contrast, gases expand to fill their containers, and this expansion leads to lower density because the mass of the gas is spread over a much larger volume.

Therefore, the correct answer reflects that the fast-moving particles of a gas are spaced apart, resulting in a lower density compared to the more compact arrangement of particles in solids.