the ratio of O2 to H2O is
1:2
therefore 6 moles of O2 will give 12 moles of H2O
The Avagadros constant is the number of atoms/molecules in one mole of anything
(this question u asked says ATOMS of water which doesn't make sense, water is made of molecules, therefore I'll work on the number of water molecules produced by 6 moles of O2)
therefore in 12 moles of H2O:
12 X 6.022x10^23 (this is the avagadros constant)
put this in your calculator and get the answer..
hope I helped!
