Final answer:
100 moles of water are formed.
Step-by-step explanation:
The balanced equation for the reaction between hydrogen gas and oxygen gas to form water is:
2 H₂(g) + O₂(g) → 2 H₂O(g)
From the equation, we can see that for every 2 moles of hydrogen gas, 2 moles of water are formed. Therefore, if we have 100 grams of hydrogen gas, which is approximately equal to 100 moles, we would form 100 moles of water.