What type of mixture is characterized by the non-uniform distribution of its components?

A mixture characterized by the non-uniform distribution of its components is known as a heterogeneous mixture. In such a mixture, the individual substances can often be distinguished and separated from one another, as they do not blend smoothly into a single phase. Examples include salads, sand and salt mixtures, or oil and water, where the components maintain their distinct properties and can be visually identified.

This contrasts with a homogeneous mixture, where the composition is uniform throughout, and the individual components are indistinguishable, such as in solutions like saltwater. Pure substances consist entirely of one type of particle and cannot be separated into simpler substances by physical methods. A colloidal solution, while it may appear somewhat uniform, contains larger particles suspended in a smaller amount and can show some characteristics of both homogeneous and heterogeneous mixtures. However, a key feature of a heterogeneous mixture is the distinct and visible separation of its components, which is what makes it the correct choice in this context.