Answer:
Both physical and chemical changes
Explanation:
From the definition of the law of conservation of mass, total mass of all the substances taking part in a chemical reaction is conserved and the number of atoms of each element in the reaction does not change when a new product is formed. Both physical and chemical changes follow the law since when the system is closed to all transfers of matter and energy, the mass of the system must remain constant over time, irrespective of the state.
