Final answer:
The particles that settle out upon standing are characteristic of a suspension, which is a heterogeneous mixture with large, visible particles that separate when not stirred.
Step-by-step explanation:
The particles of a mixture that tend to settle out upon standing are characteristic of a suspension. Suspensions are heterogeneous mixtures composed of relatively large particles that are visible or that can be seen with a magnifying glass. They appear cloudy, and unlike solutions or colloids, the suspended particles will settle due to gravity if the mixture is not continually stirred. An example of a suspension would be a mixture of mud in water. For comparison, a solution is a homogeneous mixture with particles at the molecular or ionic level that do not settle out. A colloid has larger particles than a solution but does not settle as the particles in a suspension do.