When there are one or more substances changing into new substances then a chemical or physical change has occured?

When one or more substances change into new substances, a chemical change has occurred. This process typically involves the breaking and forming of bonds, resulting in the creation of different chemical compounds with distinct properties. In contrast, a physical change involves alterations in state or appearance without changing the chemical composition of the substance. Therefore, the formation of new substances is a definitive indicator of a chemical change.