The answer is 200 mol of water.
The balanced reaction is 2(H2) + (O2) = 2(H2O)
The limiting reactant is O2 as it will be completely consumed first, before hydrogen gas. Hydrogen gas would need at least 105 mol oxygen gas to be consumed; in excess of the 100 mol O2.
Looking at the stoichiometric coefficients, the ratio between water and oxygen is 2:1.
Therefore, the water produced would be 200 moles.
