Which of the following indicates that a physical change has taken place?

• A. Vinegar reacting with baking soda to produce bubbles
• B. Ice melting into liquid water
• C. Iron rusting to form Fe2O3
• D. Paper burning to produce ash and gases

Answer: (B)

Verified step by step guidance

1. Understand the difference between physical and chemical changes: A physical change affects the form or appearance of a substance but does not change its chemical composition, while a chemical change results in the formation of one or more new substances with different chemical properties.
2. Analyze each option to determine if the chemical composition changes: For example, vinegar reacting with baking soda produces bubbles due to a chemical reaction forming new substances (carbon dioxide gas), so this is a chemical change.
3. Consider ice melting into liquid water: This process changes the state of water from solid to liquid but the chemical formula H2O remains the same, indicating a physical change.
4. Look at iron rusting to form Fe2O3: This involves iron reacting with oxygen to form a new compound (iron oxide), which is a chemical change.
5. Examine paper burning to produce ash and gases: Burning paper breaks down the material into new substances (ash, gases), so this is a chemical change.