Which of the following statements is correct about the gases which participate in photosynthesis? carbon dioxide is used up, and oxygen is produced. oxygen is used up, and carbon dioxide is produced. carbon dioxide is used up, and hydrogen is produced. hydrogen is used up, and carbon dioxide is produced.

First let's look at the photosynthesis equation:

6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂

We know that:

CO₂ is carbon dioxide
H₂O is water
C₆H₁₂O₆ is glucose
O₂ is oxygen

We also know that the left side of the reaction is the reactants (which gets used up), and the right side is what is produced.

Now, we can look at each of the choices to see which one matches the equation:

We can eliminate the last two choices automatically because there is no hydrogen atoms present on either side.
The second one is not correct because oxygen is a product, not a reactant.

Therefore, the answer is the first one because carbon dioxide is a reactant, and oxygen is a product.