Answer: Isotope Oxygen 18 will remain the same before and after the reaction because the amount of neutrons are the same in a isotope
Explanation:
Isotopes 18-17 and 16 are the most stable in earth. Keep in mind that a Isotope is an atom that has equal amount of protons and electrons but neutrons ( as you can see in the imagine below) . That is why, an isotope like oxygen 18 will remain the same in a chemical reaction, because there is only a electron transfer when doing a new molecule.