Calcium carbonate, CaCO3 , is able to remove sulfur dioxide, SO2 , from waste gases by a reaction in which the two substances react in a 1:1 stoichiometric ratio to form equimolar amounts of CaSO3 and CO2 . When 255 g of CaCO3 reacted with 135 g of SO2 , 198 g of CaSO3 were formed. Determine the percentage yield of CaSO3 .