Question

A gravel can be broken down into different kinds of substances by physical processes. No chemical reactions are needed to separate different parts of gravel into pure substances. This is because gravel is a(n)
compound
element
homogeneous mixture
heterogeneous mixture

Answer 1

heterogeneous mixture

Gravel is made of physically distinct pieces (rocks, sand, etc.) that can be separated by physical means. Compounds and elements require chemical changes to separate; homogeneous mixtures are uniform throughout.