A mixture that tends to separate when left undisturbed is known as a:

• A. Solution
• B. Emulsion
• C. Suspension
• D. Combination

Answer: (C)

Suspensions are mixtures where solid particles are dispersed in a liquid but not dissolved. Because the particles are large enough to be affected by gravity, they will slowly settle out when left undisturbed, causing the mixture to separate into a clearer liquid and a layer of settled solids. Muddy water or sand in water are common examples. A solution stays uniformly mixed because the dissolved substances are at the molecular level, so nothing settles. An emulsion involves droplets of one liquid dispersed in another and can separate over time, but the key idea is not settled solids. The defining behavior here is the visible settling of solid particles, which is characteristic of a suspension.