The species present in HNO3 are one molecule of hydrogen, one molecule of nitrogen and three molecules of oxygen.
The molar amounts can be found using the molar mass of the elements. the molar mass of hydrogen is 1, that of nitrogen is 14 and that of oxygen is 16.
HNO3= 1 + 14 + [16*3] = 63.
Therefore the relative amount of hydrogen present in HNO3 is 1, that of nitrogen is 14 and that of oxygen is 48.
