Which of the following is NOT a physical change of water?

• A. Boiling water to produce steam
• B. Electrolyzing water to produce hydrogen and oxygen gases
• C. Melting ice to form liquid water
• D. Freezing water to form ice

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the difference between physical and chemical changes. A physical change affects the form or state of a substance without changing its chemical composition, while a chemical change results in the formation of new substances with different chemical properties.
2. Step 2: Analyze each option to determine if it involves only a change in physical state or if it involves breaking chemical bonds to form new substances.
3. Step 3: Boiling water to produce steam is a physical change because it changes water from liquid to gas without altering its chemical structure (H\_2O remains H\_2O).
4. Step 4: Melting ice to form liquid water and freezing water to form ice are both physical changes because they involve changes between solid and liquid states of the same substance without changing its chemical identity.
5. Step 5: Electrolyzing water to produce hydrogen and oxygen gases is a chemical change because it involves breaking the chemical bonds in water molecules to form new substances (H\_2 and O\_2 gases), which is not a physical change.