Which statement best describes a colloid compared with a suspension?

• A. Colloids have particles that settle out quickly
• B. Colloids are mixtures with visible particles that settle out slowly
• C. Colloids have particles that remain dispersed and do not settle quickly
• D. Colloids are pure substances

Answer: (C)

Colloids are mixtures where the dispersed particles are small enough to stay spread through the medium for a long time, rather than settling out quickly. Because of their tiny size and the constant jostling from surrounding molecules (Brownian motion), these particles remain dispersed, giving the mixture a cloudy or milky appearance and preventing rapid separation. This is what sets colloids apart from suspensions, where larger particles eventually settle to form a distinct layer under gravity.

So the statement that best describes a colloid compared with a suspension is that the dispersed particles in a colloid remain dispersed and do not settle quickly. For contrast, suspensions contain larger particles that do settle over time, and colloids are not pure substances since they are mixtures. Examples include milk or fog as colloids, while sand in water is a suspension.