In which type of mixture do particles settle out because they are too heavy?

A suspension is a type of mixture in which the particles, typically larger and heavier than those in a colloid or solution, are dispersed throughout a liquid but will eventually settle out over time due to gravity. This characteristic of suspensions is a defining feature; the larger particles do not remain evenly distributed and are unable to stay suspended indefinitely.

In contrast, colloids consist of smaller particles that do not settle out quickly, giving the mixture a cloudy appearance but still allowing the particles to remain dispersed. True solutions contain solutes that are completely dissolved at the molecular level and do not settle out, resulting in a clear mixture. Similarly, a solution is a homogeneous mixture where the solute is uniformly distributed within the solvent. The particles within these types of mixtures remain suspended or dissolved rather than settling out, which distinguishes them from suspensions.