Identify whether each illustrated scenario represents a physical or chemical change.

To determine whether each process represents a physical change or a chemical change, we need to understand the key differences between the two:

- Physical Change: A change in which the substance's physical properties (e.g., shape, size, state) are altered, but its chemical composition remains unchanged. No new substances are formed.
- Chemical Change: A change in which the substance undergoes a chemical reaction, resulting in the formation of new substances with different chemical properties.

Let’s analyze each scenario step by step:

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1. Crushing a rock

- Description: Crushing a rock breaks it into smaller pieces.
- Analysis: The rock is physically broken down, but its chemical composition remains the same. No new substances are formed.
- Conclusion: Physical Change (P)

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2. Rusting of iron

- Description: Iron reacts with oxygen and water to form rust (iron oxide).
- Analysis: Rusting involves a chemical reaction where iron combines with oxygen and water to form a new substance (rust). The original iron is no longer present in its original form.
- Conclusion: Chemical Change (C)

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3. Sugar dissolving in water

- Description: Sugar dissolves in water, forming a homogeneous mixture.
- Analysis: The sugar molecules spread throughout the water, but no new substances are formed. The sugar can be recovered by evaporating the water.
- Conclusion: Physical Change (P)

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4. Slicing bread

- Description: Bread is cut into slices.
- Analysis: Slicing changes the shape and size of the bread but does not alter its chemical composition. No new substances are formed.
- Conclusion: Physical Change (P)

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5. Digestion of food

- Description: Food is broken down into simpler substances in the digestive system.
- Analysis: Digestion involves chemical reactions where enzymes break down complex molecules (e.g., proteins, carbohydrates) into simpler ones (e.g., amino acids, sugars). New substances are formed.
- Conclusion: Chemical Change (C)

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6. Baking bread

- Description: Raw dough is transformed into baked bread through heat.
- Analysis: Baking involves chemical reactions, such as the breakdown of starches into sugars and the formation of carbon dioxide gas, which causes the bread to rise. New substances are formed.
- Conclusion: Chemical Change (C)

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7. Tearing a piece of paper

- Description: Paper is torn into smaller pieces.
- Analysis: Tearing changes the shape and size of the paper but does not alter its chemical composition. No new substances are formed.
- Conclusion: Physical Change (P)

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8. Burning a candle

- Description: A candle burns, producing light and heat.
- Analysis: Burning is a chemical reaction where wax and oxygen combine to form carbon dioxide and water. New substances are formed.
- Conclusion: Chemical Change (C)

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9. Dense smoke billowing from a fire

- Description: Smoke is produced during combustion.
- Analysis: Smoke is a result of incomplete combustion, where organic materials partially burn and release particles and gases. This involves chemical reactions, forming new substances.
- Conclusion: Chemical Change (C)

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Final Answers:

1. P
2. C
3. P
4. P
5. C
6. C
7. P
8. C
9. C

Boxed Final Answer:

\[
\boxed{P, C, P, P, C, C, P, C, C}
\]