Final answer:
Ten moles of oxygen gas will react with twenty moles of water, according to the stoichiometric ratio (1:2) between oxygen and water from the balanced chemical equation for the reaction that forms water.
Step-by-step explanation:
The question is asking how many moles of water are needed to react with 10.0 moles of oxygen.
We can see that one mole of oxygen gas reacts with two moles of hydrogen gas to produce two moles of water. Therefore, the stoichiometric ratio between oxygen and water is 1:2. To find out how many moles of water are produced from 10.0 moles of oxygen, we simply double the moles of oxygen:
1 mol O2 : 2 mol water
→ 10.0 mol O2 : 20.0 mol water
So, 10.0 moles of oxygen gas will react with 20.0 moles of water.