Define a formulation in chemistry and explain how it differs from a pure substance.

A high-scoring answer should explain define a formulation as a mixture that has been designed as a useful product. Use method first, observation second, conclusion last: name the relevant test or measurement, state the observation, and then connect the result to Formulations.

This is correct because designed mixture composition is the evidence expected for formulation, and useful product properties is the result that supports the conclusion. A complete answer should use the approved objective wording, include the relevant evidence, and avoid unsupported identification claims.