Question

what do these two changes have in common?
acid rain weathering a marble statue
firing a clay pot in a hot kiln
select all that apply.
both are only physical changes.
both are chemical changes.
both are caused by heating.
both are caused by cooling.

Explanation:

1. Analyze "acid rain weathering a marble statue": Acid rain (containing acids like sulfuric acid) reacts with marble (calcium carbonate, \(CaCO_3\)) to form new substances (e.g., calcium sulfate, \(CaSO_4\)), so it's a chemical change. It's not caused by heating or cooling directly but by chemical reaction.
2. Analyze "firing a clay pot in a hot kiln": Firing clay involves chemical reactions (like dehydration, oxidation of organic matter in clay, and formation of new mineral structures) to turn soft clay into a hard pot, so it's a chemical change. It's caused by heating.
3. Evaluate options:

• "Both are only physical changes": Wrong, both are chemical changes (new substances form).
• "Both are chemical changes": Correct, as both processes result in new substances.
• "Both are caused by heating": Wrong, acid rain weathering isn't caused by heating.
• "Both are caused by cooling": Wrong, neither is caused by cooling.

Answer:

B. Both are chemical changes.