Question

A sample of beach sand contains sand particles of different colors, small pebbles, and also shells. each component contains different metals and minerals. the pebbles and shells can easily be separated from the sand. which term or terms could be used to describe this sample of sand

Answer 1

Answer is: this sample of sand is heterogeneous mixture.
Heterogeneous mixture is not uniform in composition (in this mixture different metals and minerals), but proportions of its components (in this mixture particles of different colors, small pebbles) vary throughout the sample.