Final answer:
To produce 3.0 moles of water, we would need 1.5 moles of oxygen.
Step-by-step explanation:
To find out how many moles of oxygen are needed to produce 3.0 moles of water, we need to examine the balanced chemical equation for the reaction:
2H₂ + O₂ → 2H₂O
From the equation, we can see that 2 moles of hydrogen react with 1 mole of oxygen to produce 2 moles of water. Therefore, for 3.0 moles of water, we would need half the number of moles of oxygen, which is 1.5 moles.