Which term describes a mixture with uniform composition throughout?

• A. Homogeneous mixture
• B. Mixture
• C. Heterogeneous mixture
• D. Pure substance

Answer: (A)

Uniform composition throughout means every part of the substance has the same ratio of components, so a sample taken anywhere looks the same. That’s exactly what a homogeneous mixture is: the components are evenly distributed, and you can’t distinguish different parts visually. Salt dissolved in water or air are common examples. In contrast, a heterogeneous mixture has different regions with different compositions you can often see or separate, like oil floating on water or a salad with distinct ingredients. A pure substance is not a mixture at all—it’s a single kind of matter with a fixed composition, like pure water or elemental oxygen. So for a mixture that is uniform everywhere, the best term is homogeneous mixture.