The chemical reaction for photosynthesis is 6 co2 + 12 h2o + light energy → c6h12o6 + 6 o2 + 6 h2o if the input water is labeled with a radioactive isotope of oxygen, 18o, then the oxygen gas released as the reaction proceeds is also labeled with 18o. which of the following is the most likely explanation?

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.