Chemical reactions are the processes that lead to the transformation of one set of chemical substances to another. Energy is a physical property that must be transferred to an object in order to perform work on or to heat it.
Rust forming on a car body
Water evaporating from salt water leaving salt crystals
Water freezing into ice
Dew forming on grass
Is twice as great as the mass of the reactants
Is less than the mass of the reactants
Always equals the mass of the reactants
Cannot be predicted based on the mass of the reactants
Here's an interesting quiz for you.