Final answer:
Chemical changes are useful because they allow us to understand the properties of matter and how it can be transformed into new substances with different physical and chemical properties.
Step-by-step explanation:
Chemical changes are useful because they allow us to understand the properties of matter and how it can be transformed into new substances with different physical and chemical properties. For example, the process of burning wood is a chemical change that results in the formation of ash and smoke. By studying chemical changes, we can learn about the reactivity of different substances, the conditions under which chemical reactions occur, and how to control and optimize these reactions for various applications.