Randy is building a house. He wants to put stucco on the outside walls of his house. To make stucco, he needs sand. He lives on the beach, so he decides to use the soil in his backyard. Before he can use the sand, he must remove the other substances from the soil. He separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh. Randy mixes the sand with concrete and water to make the stucco he needs. Which sentence provides the best evidence that Randy's backyard soil is a heterogeneous mixture?

Answer: He separates the larger pebbles and other debris from the finer sand by sifting it with wire mesh

Explanation: Stucco is a material used as decorative material that is coated on walls, ceilings, etc. It is made of some material, a binder and water. This material can also be sand as in this case.

A heterogeneous mixture is one and to which the constituent components vary in their size, in the proportion in which they are represented. So in a heterogeneous mixture composition of components in a particular sample is uneven. In a heterogeneous mixture of different substances, as in this case larger pebbles and other debris on one side and sand on the other make up the mixture. The components of the heterogeneous mixture do not react with each other, and from the sentence where Randy separated the larger pebbles and other debris from the sand it is noticeable that there are various substances that make up the mixture. On basis on this evidence it appears that it is a heterogeneous mixture.