Answer:
Based on the information, chlorine is an element while carbon dioxide is a compound.
Explanation:
Element:
The element is a molecule which contains two or more same atoms. As in the case of Cl2 molecule, it has two chlorine atoms.
Compound:
The compound is a molecule which contains two or more atoms of different types. As in the case of CO2, it contains carbon and oxygen atoms which are two different atoms.
