Answer: 1.6 moles H2O
Explanation: The chemical reaction in the formation of water is:
2 H2 + O2 => 2 H2O
Find first the number of moles of O2
25.6 g O2 x 1mole O2 / 32 g O2 = 0.8 moles O2
Do the mole ratio:
0.8 moles O2 x 2 moles H2O / 1 mole O2 = 1.6 moles H2O