Which of the following is NOT an example of a solution?

A mixture of oil and vinegar salad dressing is classified as a heterogeneous mixture rather than a solution. In a solution, the solute is uniformly distributed within the solvent, creating a single phase that is consistent throughout. For instance, saltwater and sugar water are homogeneous mixtures where the solute (salt or sugar) completely dissolves in the solvent (water), resulting in a clear and uniform solution. Vinegar, being a solution of acetic acid in water, also fits this definition as it maintains uniformity.

In contrast, oil and vinegar do not mix uniformly; instead, they separate into distinct layers due to their differences in polarity and density. This results in a combination that will show visible separation rather than a single-phase solution, highlighting why it does not meet the criteria for being a solution.