Answer: B- molecule
Explanation:
An atom is the smallest entity of a substance which may or may not have independent existence.
Molecule is a pure substance which is composed of similar kind of atoms.It can not be decomposed into simpler constituents using chemical reactions.Example: Hydrogen [tex]H_2[/tex]
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water [tex]H_2O[/tex]
Graphene is a crystalline allotrope of carbon and thus is a molecule as it is made up of similar kind of atoms.
