Which statement best describes a colloid?

Which statement best describes a colloid?

• A. Colloid
• B. Suspension
• C. Particles larger than in a true solution and do not settle
• D. Alloy

Answer: (C)

Colloids are mixtures with particles that are larger than those in a true solution but small enough to stay dispersed in the medium rather than settling out. The key idea is that the dispersed particles are bigger than in a true solution, which is why they have different properties, yet they don’t settle under ordinary conditions because Brownian motion keeps them suspended. That combination is exactly captured by the statement: the particles are larger than in a true solution and do not settle. The other descriptions don’t fit as well: a true solution has particles that are too small to see and stay uniformly mixed, a suspension contains larger particles that eventually settle, and an alloy is a solid mixture of elements at the atomic level, not a dispersed phase in a medium.

Colloids are mixtures with particles that are larger than those in a true solution but small enough to stay dispersed in the medium rather than settling out. The key idea is that the dispersed particles are bigger than in a true solution, which is why they have different properties, yet they don’t settle under ordinary conditions because Brownian motion keeps them suspended. That combination is exactly captured by the statement: the particles are larger than in a true solution and do not settle.

The other descriptions don’t fit as well: a true solution has particles that are too small to see and stay uniformly mixed, a suspension contains larger particles that eventually settle, and an alloy is a solid mixture of elements at the atomic level, not a dispersed phase in a medium.