What is the main difference between homogeneous and heterogeneous mixtures?

Correct answer: Homogeneous has uniform composition and heterogeneous has non-uniform composition

A homogeneous mixture has the same composition and properties throughout a sample, so one part appears like every other part. Salt solution is a familiar example when the salt is evenly dissolved. In a heterogeneous mixture, the composition is not uniform; different parts may contain different amounts or visibly different components. Sand mixed with water illustrates this difference because the particles and regions can be distinguished.

Option A is correct because it clearly states uniform composition for a homogeneous mixture and non-uniform composition for a heterogeneous mixture. A homogeneous mixture is not necessarily an element, because it may contain several substances. A heterogeneous mixture is not pure, and both types do contain components. The distinction is based on uniformity, not on whether matter has components.