Final answer:
To generate two moles of H₂O, one mole of O₂ is needed, based on the stoichiometric relationship in the balanced chemical equation.
Step-by-step explanation:
When looking at the balanced chemical equation 2 H₂ + O₂ → 2 H₂O, it indicates the ratios of reactants and products involved in the reaction. Specifically, this equation tells us that for every mole of O₂ you need, you will produce two moles of H₂O. If you want to generate two moles of H₂O, you will require one mole of O₂ according to this stoichiometric relationship. The balanced equation is reflective of molar amounts, showing that two moles of hydrogen react with one mole of oxygen to produce two moles of water.