Question: how many grams of hydrogen atoms are present in 16.4 g of water?
Answer: Water has a molar mass of 18.01528 g/mol≈18 g/mol . Since water has a chemical formula of H2O , there will be 2 moles of hydrogen in every mole of water. In one mole of water, there will exist approximately 6.02⋅1023 water molecules.