MIXTURES

A homogeneous mixture is a solid, liquid or gaseous mixture that has the same proportions of its components throughout any given sample. Conversely, a heterogeneous mixture has components in which proportions vary throughout the sample. ... An example of a homogeneous mixture is air.

A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers. Each of the layers is called a phase. Oil and water do not mix, instead forming two distinct layers called phases.