The mass per cent of different elements present in sodium sulphate, Na2SO4 respectively are

Mass per cent of an element = = Mass of that element in the compound  Molar mass of the compound ×100 Molar mass of Na2SO4 =(2×22.99)+32.06+(4×16.00)                                      = 142.04 g Mass per cent of sodium =45.98×100142.04=32.37 Mass per cent of sulphur =32.06×100142.04=22.57 Mass per cent of oxygen =64×100142.04=45.06