Which of the following laboratory procedures best illustrates the law of conservation of mass?Calculating the number of atoms in 11 g of NaUsing 250 g of impure Cu to obtain 200 g of pure CuHeating 32 g of S and 56 g of Fe to produce 88 g of FeS and unused reactantsBurning 2.4 g of Mg in an open crucible to produce 2 g of MgO and unused reactants