How is a "solution" defined in chemistry?

In chemistry, a "solution" is defined as a homogeneous mixture of two or more substances. This means that the components of a solution are uniformly distributed at the molecular level, resulting in a consistent composition throughout. In a solution, one substance (the solute) is dissolved in another substance (the solvent), creating a single-phase mixture that appears uniform to the observer.

This definition distinguishes solutions from other types of mixtures. For instance, a homogeneous mixture generally refers to mixtures where the composition is uniform, but in the case of solutions specifically, the solute is present at the molecular level within the solvent. This is why solutions are typically transparent and do not exhibit any separation of components, unlike suspensions, which are heterogeneous mixtures that can settle over time and contain larger particles that are not dissolved. Additionally, while choices referring to gases and compounds emphasize aspects of mixtures and chemical compositions, they do not capture the essence of homogeneity or the specific interaction between solute and solvent found in solutions.

Therefore, the correct choice accurately reflects the definition of a solution in chemistry as a homogeneous mixture of two or more substances.