How many moles of C6H12O6 are consumed if 6 moles of O2 are consumed?

This reaction is known as respiration and in order to understand the stoichometry better, we first write the reaction equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

From the equation, we can see that the molar ratio between glucose and oxygen is 1 : 6. Therefore, we can see that if 6 moles of oxygen are consumed, one mole of glucose will be consumed.