12g of alkaline earth metal gives 14.8 g of its nitride. Atomic weight of metal is ____ ?

general formula of alkaline earth metal nitride is M3N212g of metal form 14.8 g of metal nitride Amount of nitrogen in metal nitride is (14.8-12) g=2.8 g12g of metal react with 2.8g of nitrogen Then 28g gram of nitrogen react with 28×122.8g of metal =120 gFor 28g of nitrogen, three moles of metal atoms combine Therefore, atomic weight of alkaline earth element is 1203=40g