During photosynthesis, the number of carbon dioxide molecules remains unchanged. This is because the overall equation for photosynthesis can be summarized as:
6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂
In this process, six carbon dioxide molecules are used to produce one molecule of glucose and six molecules of oxygen, while the water molecules are also consumed and glucose is produced. However, the number of carbon dioxide molecules (6) remains consistent in the overall reaction.