Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction, all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2S). What scientific law explains why his prediction will be correct? A. The Law of Conservation of Matter
B. The Law of Conservation of Energy
C. The Law of Conservation of Motion
D. The Theory of Gravity