Which term describes a variable composition with different parts visible?

• A. Pure substance
• B. Heterogeneous mixture
• C. Suspension
• D. Mechanical mixtures

Answer: (B)

Heterogeneous mixtures have a variable composition with different parts visible. In these mixtures, the substances don’t blend into a single uniform material, so you can usually see the separate components, either with the naked eye or under simple observation. This contrasts with a pure substance, which has the same composition throughout. A suspension is a specific type of heterogeneous mixture where solid particles are dispersed in a liquid or gas and can settle out over time, but the general idea of “visible parts” fits heterogeneous mixtures best. Mechanical mixtures describe mixtures where components are physically combined but still distinct, which also reflects visible parts, yet the standard term educators use for this broad idea is heterogeneous mixture.