Which example shows a physical change?

Which example shows a physical change?

• A. Wood burning.
• B. Ice melting into water.
• C. Rusting of iron.
• D. Digestion of food.

Answer: (B)

A physical change is when matter changes its form or state without becoming a new substance. Ice melting into water fits this because the substance stays as H2O; it simply changes from a solid to a liquid. Energy from heat allows the water molecules to move more freely, but no new chemical is formed, and the change can be reversed by freezing. The other examples involve chemical changes. Wood burning changes matter into ash and various gases through a chemical reaction with oxygen. Rusting of iron creates iron oxide, a new substance with different properties. Digestion breaks down molecules and forms new ones inside the body.

A physical change is when matter changes its form or state without becoming a new substance. Ice melting into water fits this because the substance stays as H2O; it simply changes from a solid to a liquid. Energy from heat allows the water molecules to move more freely, but no new chemical is formed, and the change can be reversed by freezing.

The other examples involve chemical changes. Wood burning changes matter into ash and various gases through a chemical reaction with oxygen. Rusting of iron creates iron oxide, a new substance with different properties. Digestion breaks down molecules and forms new ones inside the body.