Question: how many hydrogen atoms are present in 3.14 mol of h2o?
Answer: You have 3.14 moles of water. For each mole of water, there are two moles of 'H' and one mole of 'O'. So there will be 2 X 3.14 moles of 'H' or 6.28 moles of hydrogen atoms, remembering that a hydrogen atom is simply 'H'.