Which describes a mixture with small, undissolved particles that do not settle out?

Which describes a mixture with small, undissolved particles that do not settle out?

• A. Suspension
• B. Acid
• C. Colloid
• D. Solute

Answer: (C)

This question is about how particle size and settling behavior distinguish different mixtures. A colloid consists of very tiny particles that are not dissolved in the medium but remain dispersed throughout. Because the particles are so small and constantly jostled by the surrounding fluid, they don’t settle out over time. They stay evenly distributed, giving the mixture a cloudy or milky appearance and often exhibiting the Tyndall effect, where light scatters as it passes through. That combination of small, undissolved particles that stay suspended explains why the description fits a colloid. In contrast, a suspension has larger particles that will settle out if left alone, a solution has solute dissolved so you don’t see undissolved particles, and an acid is simply a chemical property or substance, not a type of mixture.

This question is about how particle size and settling behavior distinguish different mixtures. A colloid consists of very tiny particles that are not dissolved in the medium but remain dispersed throughout. Because the particles are so small and constantly jostled by the surrounding fluid, they don’t settle out over time. They stay evenly distributed, giving the mixture a cloudy or milky appearance and often exhibiting the Tyndall effect, where light scatters as it passes through.

That combination of small, undissolved particles that stay suspended explains why the description fits a colloid. In contrast, a suspension has larger particles that will settle out if left alone, a solution has solute dissolved so you don’t see undissolved particles, and an acid is simply a chemical property or substance, not a type of mixture.