Question: Which of the following statements is true?
According to the law of conservation of mass, the total mass of the system remains unchanged, also with a chemical change. The total mass of the products equals the total mass of the reactants.
Sometimes, other substances (reagents) to react with to form a new substance (product). This is a temporary change. However, when the reactant is fully converted into new products, and the chemical change takes place.
Therefore, a chemical change is permanent and irreversible while the physical change is temporary and reversible.