Answer:
Since 2H₂ + O₂ ---> 2H₂O
We need 2 moles of hydrogen for each mole of oxygen
So, we need 2(6) = 12 moles of H₂ but since we only have 10 moles,
H₂ is the limiting reagent
So since 2 moles of H₂ gives 2 moles of water,
10 moles of H₂ will give rise to 10 moles of Water with 1 mole of remaining oxygen