What change in matter produces one or more new substances?

• A. Chemical change
• B. Physical change
• C. Phase change
• D. Nuclear change

Answer: (A)

The key idea is that forming one or more new substances requires breaking and forming chemical bonds so the atoms are arranged into different molecules with new properties. This happens in a chemical change, where the material’s composition actually changes. For example, burning methane creates carbon dioxide and water—substances with different properties than the original methane. In contrast, a phase change or other physical change only alters appearance or state (solid, liquid, gas) without changing the chemical makeup, so no new substances are produced. Nuclear changes involve changes in the atomic nucleus and can create different elements or isotopes, which is a different category from typical chemical changes. So the change that yields new substances is a chemical change.