What is true about the composition of a homogeneous mixture?

A homogeneous mixture is defined by its uniform composition throughout, meaning that every part of the mixture has the same characteristics and properties. This uniformity is key to understanding why all components must be in the same physical state.

For example, in a solution like saltwater, both salt and water are in the liquid phase, resulting in a consistent composition that appears the same throughout. If the components were in different phases—such as solid and liquid or gas and liquid—the mixture would not be considered homogeneous, as different phases would lead to visible separations or variations in composition.

In contrast, options referring to the mixture containing substances in different phases, varying in composition throughout, or exclusively containing gaseous components would describe different types of mixtures or states that do not reflect the true nature of a homogeneous mixture. Hence, the requirement that all components be in the same physical state is essential for a mixture to be classified as homogeneous.