2 atoms:
one mole is 6.022 times 10 to the 23 atoms according to Avogadro's Number, there are 2 Hydrogens in water, H20, so therefore 2 times 6.022 times to 10 to the 23 is your answer. O which means that ever molecule of water has 2 atoms of hydrogen (H) and one atom of oxygen (O)
