Question

which of the following examples is not considered a pure substance? a water molecule fruit punch carbon

Explanation:

A pure substance has a fixed - composition. A water molecule ($H_2O$) is a pure substance as it has a definite chemical formula. Carbon is an element and thus a pure substance. Fruit punch is a mixture of different substances like water, fruit juices, sugars etc., and does not have a fixed composition.

Answer:

fruit punch