Question

which of the following is not a pure substance? * 5 points water milk oxygen carbon dioxide

Explanation:

A pure substance has a fixed - composition. Water ($H_2O$), oxygen ($O_2$), and carbon dioxide ($CO_2$) are pure substances as they have definite chemical compositions. Milk is a mixture of water, fats, proteins, lactose, and other substances, so it is not a pure substance.

Answer:

milk