What is a colloid?

What is a colloid?

• A. A pure compound.
• B. A solution with dissolved gas.
• C. A solid-liquid mixture with no phase separation.
• D. A mixture in which minute particles are spread evenly throughout another substance.

Answer: (D)

Colloids are mixtures in which minute particles are dispersed throughout another substance, forming a stable dispersion rather than a true solution. The dispersed particles are small enough to stay suspended and give the mixture a uniform appearance, yet large enough to scatter light (the Tyndall effect) and not settle quickly. This description matches the idea of tiny particles spread evenly throughout another substance, which is the defining feature of a colloid. Think of examples like milk, fog, or mayonnaise to see how droplets or particles are dispersed in a continuous medium. A describes a pure compound, B describes a true solution with dissolved gas, and C describes a solid–liquid arrangement that doesn’t capture the dispersed-particle character of colloids.

Colloids are mixtures in which minute particles are dispersed throughout another substance, forming a stable dispersion rather than a true solution. The dispersed particles are small enough to stay suspended and give the mixture a uniform appearance, yet large enough to scatter light (the Tyndall effect) and not settle quickly. This description matches the idea of tiny particles spread evenly throughout another substance, which is the defining feature of a colloid. Think of examples like milk, fog, or mayonnaise to see how droplets or particles are dispersed in a continuous medium. A describes a pure compound, B describes a true solution with dissolved gas, and C describes a solid–liquid arrangement that doesn’t capture the dispersed-particle character of colloids.