Answer: The correct answer is atoms, molecules and compound.
Explanation:
Atoms are defined as the smallest unit of chemical element which cannot be further divided. These are combine together to form molecules or compounds. For Example: Cl, N etc.
Molecules is defined as the group of atoms that are bonded together and they represent the smallest fundamental unit of chemical compound. It can be molecules of element (combination of same kind of atoms) or molecules of compound (combination of different kind of atoms). For Example: [tex]N_2,H_2O[/tex] etc..
Compounds are defined as the chemical substance which is formed from the combination of two or more atoms of different element. For Example: [tex]H_2O,CO_2[/tex]
Hence, the correct answer is atoms, molecules and compound.
