Which of the following statements is true about suspensions?

The correct statement regarding suspensions is that they can separate into distinct layers over time. Suspensions are heterogeneous mixtures where solid particles are dispersed within a liquid but do not dissolve. Over time, due to gravity, the solid particles within the suspension may settle at the bottom, leading to distinct layers forming in the container. This characteristic distinguishes suspensions from solutions, where the dissolved substances remain uniformly distributed.

The other statements about suspensions highlight common misconceptions. For instance, suspensions cannot generally be filtered to remove dissolved substances because they are typically comprised of larger particles that do not dissolve, meaning filtration would not apply as it does in solutions. Furthermore, suspensions do not remain stable indefinitely without stirring; they typically require continual agitation to keep the solid particles suspended in the liquid, preventing them from settling. Lastly, suspensions are not typically homogeneous mixtures, as their nature involves visible differences in composition, contrary to the uniform characteristics of homogeneous mixtures.