Chemistry Regents Practice Test

In chemistry, a solution is defined as a homogeneous mixture of two or more substances, meaning that the components are evenly distributed throughout the mixture at the molecular or ionic level. In a solution, the constituents cannot be differentiated and appear uniform, which is a key characteristic that distinguishes solutions from other types of mixtures.

While a solid dissolved in a liquid is often an example of a solution, it is not the sole requirement. Solutions can also consist of gases (like air, which is a mixture of nitrogen, oxygen, and other gases) or exist in solid form (such as alloys). This broader definition emphasizes the importance of homogeneity rather than the specific states of matter involved.

The other options highlight misconceptions about what a solution is. A pure substance cannot encompass mixtures of various components, distinct layers indicate a heterogeneous mixture rather than a uniform solution, and the mention of a solid dissolved in a liquid is overly specific when defining a solution. Thus, the best representation of a solution in chemistry is its classification as a homogeneous mixture of two or more substances.