Which of the following events always involves a chemical change?

• A. Boiling
• B. Conducting
• C. Burning
• D. Melting

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the difference between physical and chemical changes. A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of one or more new substances with different properties.
2. Step 2: Analyze each event given: Boiling is a physical change where a liquid turns into a gas without changing its chemical identity.
3. Step 3: Conducting (usually referring to conducting electricity or heat) is a physical process that does not alter the chemical composition of the material.
4. Step 4: Melting is a physical change where a solid turns into a liquid, again without changing the chemical identity of the substance.
5. Step 5: Burning is a chemical change because it involves a chemical reaction (combustion) that produces new substances such as carbon dioxide, water, and other compounds, indicating a change in chemical composition.