5.43 g sample of a pure salt, M2 SO4 , was dissolved in water. The ion was precipitated by adding excess BaCl2 solution when 4.67 g BaSO4 was obtained. How many moles of were precipitated? Determine the molecular mass of M2 SO4 , and hence, the atomic mass of M. [O =16, S = 32, Ba = 137.3]