Which of the following best explains why the melting of ice is not considered a chemical change?

• A. A chemical reaction occurs when ice melts, forming hydrogen and oxygen gases.
• B. Melting ice produces new substances with different chemical properties.
• C. The melting of ice involves breaking chemical bonds within the H_2O molecules.
• D. The process does not alter the chemical composition of H_2O; only its physical state changes.

Answer: (D)

Verified step by step guidance

1. Understand the difference between a chemical change and a physical change: A chemical change results in the formation of new substances with different chemical properties, while a physical change affects only the physical state or appearance without altering the chemical composition.
2. Analyze the melting of ice: When ice melts, it changes from solid to liquid water, but the molecules remain H_2O throughout the process.
3. Recognize that no new substances are formed during melting: The chemical bonds within each H_2O molecule remain intact; only the arrangement and movement of molecules change.
4. Conclude that melting ice is a physical change because the chemical identity of the substance (H_2O) does not change, only its physical state changes from solid to liquid.
5. Therefore, the best explanation is that the process does not alter the chemical composition of H_2O; only its physical state changes.