Which equation represents photosynthesis?

• A. CO2 + H2O -> CH2O
• B. 6CO2 + 6H2O -> C6H12O6 + 6O2
• C. C6H12O6 + 6O2 -> CO2 + 6H2O
• D. 6O2 + 6H2O -> C6H12O6 + CO2

Answer: (B)

Photosynthesis uses light energy to combine carbon dioxide and water into a sugar (glucose) and oxygen. The properly balanced way to show this is 6 CO2 + 6 H2O -> C6H12O6 + 6 O2. This shows six molecules of carbon dioxide and six of water producing one molecule of glucose and six molecules of oxygen, capturing energy in the glucose the plant makes.

The other representations aren’t correct for this process. One version is an unbalanced, simplified idea that suggests a generic carbohydrate without showing the actual oxygen gas produced. Another depicts the reverse process of cellular respiration, where glucose and oxygen break down into carbon dioxide and water. The last option isn’t a balanced or valid depiction of the reaction either, mixing reactants and products in a way that doesn’t reflect how photosynthesis occurs.