Answer:when a chemical reaction occurs with only one substance, the atoms of that substance rearranges to form new bonds to make the products.
Explanation: During chemical reaction, the bonds between the reactants are broken and the atom bonds in new ways to form products that are chemically and physically different from the reactants.
Example is the breakdown reaction of hydrogen peroxide(the reactant) into water and oxygen( products). Here, 2 molecules of hydrogen peroxide is broken down to form 2 molecules of water and one molecule of oxygen. The atoms that started out in the hydrogen peroxide molecules are rearranged to form water molecules and oxygen molecules.
Because the temperature of the place its contained in is constantly changing, for example, if you put a room temperature item in the fridge it will become cold, or whatever the temperature you set your fridge to.
