Which type of change occurs when liquid water evaporates and becomes water vapor?

• A. A nuclear change, because the nuclei of water molecules are altered.
• B. A chemical change, because new substances are formed.
• C. No change occurs, because water vapor is identical to liquid water in every way.
• D. A physical change, because the chemical composition of water remains the same.

Answer: (D)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form or physical properties of a substance without changing its chemical composition, while a chemical change results in the formation of new substances with different chemical properties.
2. Identify what happens during evaporation: Liquid water changes to water vapor (gas) by gaining enough energy to overcome intermolecular forces, but the water molecules themselves remain H\_2O.
3. Analyze whether the chemical composition changes: Since the molecules remain H\_2O and no new substances are formed, the chemical composition stays the same.
4. Consider if the nuclei of the molecules are altered: Nuclear changes involve changes in the nucleus of atoms, which does not happen during evaporation.
5. Conclude that evaporation is a physical change because the state of matter changes from liquid to gas, but the chemical identity of water remains unchanged.