a. The photosynthetic conversion is through combustion of the glucose. The balanced chemical reaction is written below:
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O
b. Yes, it is because it has to obey the Law of Conservation of mass. There are a total of 6 atoms of C, 12 atoms of H and 18 atoms of O both in the left and right side of the reaction.
c. Yes. The stoichiometric coefficients can represent as atoms, molecules or moles.