Final answer:
A homogeneous mixture consists of only one phase as it has a uniform composition throughout, unlike a heterogeneous mixture, which consists of two or more phases.
Step-by-step explanation:
A homogeneous mixture consists of a single phase with a uniform composition throughout. By definition, in chemistry, a phase refers to any part of a sample that has uniform composition and properties. When we talk about homogeneous mixtures, we are referring to mixtures like salt dissolved in water or filtered coffee, where the components are so thoroughly mixed that only one phase is visible and has the same uniform appearance and composition throughout.
On the contrary, a heterogeneous mixture contains two or more phases. An example of this is oil mixed with water; they separate into two distinct layers, each layer representing a different phase. Since the composition in a heterogeneous mixture varies from one part of the mixture to another, each region with a uniform composition would be considered a separate phase.
Therefore, the answer to the question is that a homogeneous mixture has one phase.