What happens to the particles in a suspension if left undisturbed?

In a suspension, particles are dispersed throughout a liquid but are not dissolved in it. If left undisturbed, the natural gravitational forces acting on these particles will cause them to settle at the bottom over time. This settling occurs because the particles are typically larger and denser than the liquid they are suspended in, leading to a phase separation where the solid particles aggregate and form a sediment at the bottom of the container.

The other choices do not accurately describe the behavior of particles in a suspension. For example, dissolving completely pertains to solutions rather than suspensions. Suspensions do not remain suspended indefinitely; they will eventually separate. Lastly, forming a gel-like consistency is not characteristic of standard suspensions, which, by definition, consist of discrete particles rather than a homogenous gel structure. Therefore, the correct understanding of a suspension's behavior confirms that particles will settle when left undisturbed.