Which gas is a byproduct of photosynthesis?

During the process of photosynthesis, plants, algae, and some bacteria convert carbon dioxide and water into glucose and oxygen using sunlight as the energy source. The overall chemical equation for photosynthesis can be simplified as:

6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂

In this equation, the initial reactants are carbon dioxide and water, and the end products include glucose (which is used as energy and structural material by the plant) and oxygen. The oxygen produced during this process is released into the atmosphere as a byproduct. This release of oxygen is crucial for life on Earth, as it contributes to the air we breathe.

In contrast, carbon dioxide and nitrogen are not byproducts of photosynthesis. Carbon dioxide is actually one of the key ingredients needed for photosynthesis, while nitrogen is not involved in this process at all. Hydrogen does play a role in the light-dependent reactions of photosynthesis but does not appear as a byproduct in the same way that oxygen does. Therefore, the correct answer is oxygen, as it is the gas released during photosynthesis.