Question

How many moles of hydrogen are required to make 32 moles of water?

Answer 1

You multiply 32 by 2, since there are two hydrogens in every water molecule.

Answer 2

We know that there are 2 moles of H in 1 mole of water. How many moles of H are there in 32 moles of water?
 
H2O ----------------- H
1 mol --------------- 2 mols
32 mol ------------- x
 
1 . X = 32. 2 ⇒ X = 64 mols of H

Answer:
$\boxed{\boxed{64\: mols\: of\: Hydrogen}}$