What distinguishes a homogeneous mixture from a heterogeneous mixture?

A homogeneous mixture is characterized by a uniform composition throughout its entirety, meaning that the different components are evenly distributed and not easily distinguishable from one another. This uniformity is what sets it apart from a heterogeneous mixture, where the individual substances remain distinct and can often be observed separately.

For example, saltwater is a homogeneous mixture; the salt dissolves completely in the water, resulting in a consistent mixture that looks the same throughout. In contrast, a salad is a heterogeneous mixture; you can see and identify the different ingredients, which do not blend into a uniform substance.

The other options do not accurately define the differences between homogeneous and heterogeneous mixtures. The notion that a heterogeneous mixture contains only solids is incorrect, as heterogeneous mixtures can consist of liquids and gases as well, like oil and vinegar. Similarly, a homogeneous mixture cannot typically be easily separated by filtration; rather, it requires different methods like distillation or evaporation, while a heterogeneous mixture can often be separated by physical means such as filtering. Lastly, a heterogeneous mixture is defined by its lack of uniform appearance, contrasting with the uniform appearance found in homogeneous mixtures.