The smallest unit of a substance that behaves like the substance is

Answer : The smallest unit of a substance that behaves like the substance is, molecule.

Explanation :

Pure substance : It is defined as a substance that is made by the combination of only one type of atom or only one type of molecule.

Compound : It is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.

Element : It is a pure substance which is composed of atoms of similar elements.

Molecule : It is the smallest particle in the chemical compound or chemical element or a substance that has the same chemical properties of that compound or element.

Hence, the smallest unit of a substance that behaves like the substance is, molecule.