Which term refers to a mixture with tiny particles dispersed throughout a medium, often not settling quickly?

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

Answer: (B)

Colloid describes a mixture where very small particles are dispersed throughout a medium and remain suspended rather than settling out. These particles are larger than molecules but still tiny—often in the nanometer range—so gravity doesn’t pull them down quickly. Brownian motion and interactions with the surrounding fluid help keep them dispersed, giving the mixture a look that’s uniform at a glance while still being heterogeneous on a microscopic level. You can also see light scattering in colloids, known as the Tyndall effect, which hints at the presence of these dispersed particles.

This differs from a suspension, where larger particles eventually settle and separate into layers. It also differs from a solution, where the solute is dissolved at the molecular level and no separate particles remain visible. It’s related to an emulsion, which is a type of colloid in which droplets of one liquid are dispersed in another immiscible liquid.