Why is it important to learn about chemical reactions?What must be the same before and after a reaction?

Chemical reactions help us understand the properties of matter. By studying the way a sample interacts with other matter, we can learn its chemical properties. These properties can be used to identify an unknown specimen or to predict how different types of matter might react with each other. For any chemical reaction , the mass of the reactants before the reaction should be equal to the mass of products formed after the reaction.

Deposition is the transition of matter going from gas to solid without passing through the liquid phase.a.) gas—-> solid