Which statement describes a homogeneous mixture?

• A. Uniform composition; can't see different parts
• B. Not uniform; you can see parts
• C. A pure substance
• D. A compound

Answer: (A)

The main idea is that a homogeneous mixture has a uniform composition throughout, so every part of the sample has the same ratio of components and you can’t distinguish different parts by appearance. In such mixtures the components are spread evenly, like sugar dissolved in water or the air around us. A pure substance, on the other hand, is a single kind of matter with a fixed composition, which is why it isn’t a mixture at all. A compound is a type of pure substance made from two or more elements chemically bonded together, not just a mixture of separate substances. A nonuniform mixture shows visible parts that you can tell apart, which is the opposite of a homogeneous mixture. So describing uniform composition and invisibility of the different parts best captures what a homogeneous mixture is.