Which of the following laboratory procedures best illustrates the law of conservation of mass? (Assume the product of the reaction includes the mass of any unused reactants.) (3 points)
Reacting 12 g of C with 32 g of O2 to form 44 g of CO2
Weighing 100 g of Cu powder and 100 g of Fe filings
Heating 100 g of CaCO3 to produce 56 g of CaO
Dissolving 10 g of NaCl in 100 g of water