Answer:
The chemical reaction for photosynthesis is if the input water is labeled
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.