What defines a solution in chemistry?

In chemistry, a solution is defined as a homogenous mixture of two or more substances. This means that the components of the solution are uniformly distributed at the molecular level, resulting in a single phase. Solutions can be made from different types of substances, which could include solids, liquids, or gases.

For example, when table salt (solid) dissolves in water (liquid), it forms a saltwater solution where the salt ions are evenly dispersed throughout the water, creating a uniform mixture with properties that are consistent throughout. This highlights the key characteristic of solutions: the uniformity of composition and the lack of visible boundaries between different components.

Other options do not accurately capture this definition. A mixture of gases alone does not necessarily define a solution, as it might not be uniform. A water-based mixture is too restrictive since solutions can exist in any phase. Lastly, a solid combined with a liquid does not guarantee a homogeneous mixture; the solid may not dissolve, leading to a heterogeneous mixture instead. Therefore, the definition of a solution as a homogenous mixture encompasses the broader characteristics and behaviors observed in chemical solutions.