Question

what is a pure substance made of? different compounds mixed with elements a combination of elements and compounds multiple elements mixed together a single element or compound

Explanation:

A pure substance has a definite and constant composition. It can either be a single - element (like gold, Au) or a single - compound (like water, H₂O). Mixtures of different compounds with elements, combinations of elements and compounds, or multiple elements mixed together are not pure substances.

Answer:

A single element or compound