Which of the following best explains why boiling water is considered a physical change?

• A. Boiling water results in the formation of hydrogen and oxygen gases.
• B. Boiling water produces new substances with different chemical properties.
• C. Boiling water only changes its state from liquid to gas without altering its chemical composition.
• D. Boiling water involves breaking chemical bonds within H2O molecules.

Answer: (C)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form or state of a substance without changing its chemical identity, while a chemical change results in the formation of new substances with different chemical properties.
2. Identify what happens during boiling water: When water boils, it changes from liquid to gas (steam), which is a change in physical state, not in chemical composition.
3. Recognize that the chemical formula of water (H2O) remains the same before and after boiling, meaning no new substances are formed and no chemical bonds within the water molecules are broken.
4. Evaluate the given options by comparing them to the definition of physical and chemical changes, focusing on whether the chemical composition changes or not.
5. Conclude that boiling water is a physical change because it only involves a change in state (liquid to gas) without altering the chemical identity of water.