A. Because they are compounds, they cannot be pure substances.
Explanation:
The false statement from the given choices is that because they are compounds they cannot be pure substances. In fact, because they are compounds they are pure substances.
Pure substances are made up of elements and compounds and they have the following properties:
All parts are the same throughout
Composition is definite
They cannot easily be separated or broken
Separation by physical method is not easy
They have unique sets of physical and chemical properties.
