How many moles of water are produced from 15 moles of oxygen?

30 moles

Explanation:

Water is H2O, meaning there is 2 Hydrogen atoms and 1 Oxygen atom. Oxygen is O2, because it is a diatomic molecule. (Hydrogen is also a diatomic molecule, so H2)

The equation, balanced, would have to be: 2H2 + O2 > 2H2O

I multiply 15 moles O2 by the molar ratio of (hydrogen/oxygen)

15 mol. O2 *  (2 mol. H2/1 mol O2) = 30 moles of water