We are talking about chemical reaction here. In a chemical reaction, substances that react are called reactants, and substances which are formed are called products. Atoms in the reactants break their bond, rearrange themselves and form new bonds to make the product. So no atoms are added or removed, which is called law of conservation of atoms/mass.
Answer:
Oxygen is moved around the body of an echinoderm in its C. water vascular system.
Smog. Im pretty sure smog is the only unhealthful air pollution on this list.
