What defines a solution in chemistry?

A solution in chemistry is characterized as a homogeneous mixture of two or more substances. This homogeneity means that the composition is uniform throughout the mixture, and the different components cannot be distinguished from one another at the molecular level. In a solution, one substance, known as the solute, is dissolved in another substance, known as the solvent.

This definition encompasses a wide variety of solutions, including those formed by liquids, solids, or gases. For instance, when salt (the solute) dissolves in water (the solvent), it forms a saline solution, which is a classic example of a liquid solution.

Other options do not accurately define a solution in the same comprehensive way. For example, a mixture of gases may not necessarily form a solution if the gases can be easily distinguished from one another. Similarly, while a solid dispersed in a liquid might refer to a suspension rather than a true solution, a combination of elements that cannot be separated describes a compound, not a solution. Thus, the definition of a solution as a homogeneous mixture properly captures its fundamental characteristics.