Which of the following changes does not involve chemical reactions?

• A. Rusting of iron
• B. Burning of wood
• C. Melting of ice
• D. Digestion of food

Answer: (C)

Verified step by step guidance

1. Understand that a chemical reaction involves the making or breaking of chemical bonds, resulting in new substances with different properties.
2. Analyze each option to determine if it involves a chemical change:
3. Rusting of iron involves iron reacting with oxygen to form iron oxide, which is a new substance, so it is a chemical reaction.
4. Burning of wood involves combustion, where wood reacts with oxygen to produce new substances like carbon dioxide and water, so it is a chemical reaction.
5. Melting of ice is a physical change where solid water changes to liquid water without altering its chemical composition, so it does not involve a chemical reaction.
6. Digestion of food involves breaking down complex molecules into simpler ones through chemical reactions catalyzed by enzymes, so it is a chemical reaction.