Among 4 mol of H2O and 5 mol of CH3COOCH, 5 mol of CH3COOH contains the greatest number of hydrogen atoms. This is because in 4 mol of H2O there are 4N molecules where N is equal to Avogadro’s number. In 5 mol of CH3COOH, there are 5N molecules where N is equal to Avogardro’s number. Also, the number of hydrogen atoms in the formula is the same as the total number of hydrogen atoms in the sample. Therefore, in 4 mol of H2O there are 8N hydrogen atoms while in 5 mol of CH3COOH there are 20N hydrogen atoms. Therefore, 5 mol of CH3COOH contains the greatest number of hydrogen atoms.