"Worksheet for students to determine whether given statements about physical and chemical changes are true or false."

To solve the worksheet, we need to determine whether each statement is true or false based on the definitions of physical changes and chemical changes:

- Physical Change: A change in which the physical properties of a substance (such as state, shape, size) are altered, but the chemical composition remains the same. No new substances are formed.
- Chemical Change: A change in which the chemical composition of a substance is altered, resulting in the formation of new substances with different properties.

Let's analyze each statement:

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1. Evaporation is a physical change.

- Explanation: Evaporation involves a change in the state of matter from liquid to gas. The substance itself does not change chemically; it only changes its physical state.
- Answer: True

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2. Ice cream melting is a chemical change.

- Explanation: Melting ice cream involves a change in state from solid to liquid. This is a physical change because the chemical composition of the ice cream remains the same.
- Answer: False

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3. Wood burning is a physical change.

- Explanation: Wood burning involves combustion, where wood reacts with oxygen to produce carbon dioxide, water vapor, and ash. This is a chemical change because new substances are formed.
- Answer: False

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4. Water mixing with oil is a physical change.

- Explanation: Mixing water and oil does not result in the formation of new substances. It is simply a combination of two substances without any chemical reaction.
- Answer: True

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5. Air inflating a tire is a chemical change.

- Explanation: Inflating a tire involves compressing air into the tire. This is a physical change because the air molecules are being compressed but their chemical composition remains unchanged.
- Answer: False

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6. Marshmallows roasting on a fire is a chemical change.

- Explanation: Roasting marshmallows involves heating them, which causes chemical reactions that break down sugars and proteins, forming new compounds. This is a chemical change.
- Answer: True

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7. Marshmallows cut in half is a chemical change.

- Explanation: Cutting marshmallows in half is a physical change because no new substances are formed; the marshmallows are simply divided into smaller pieces.
- Answer: False

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8. Chemical changes can be easily reversed.

- Explanation: Chemical changes typically involve the formation of new substances, and reversing these changes often requires different chemical processes. They are generally not easily reversible.
- Answer: False

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9. Physical changes can be easily reversed.

- Explanation: Physical changes, such as melting, freezing, or cutting, do not alter the chemical composition of a substance. These changes can usually be reversed by applying the opposite process (e.g., freezing melted water to get ice).
- Answer: True

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10. Fermenting cheese and grating cheese are both physical changes.

- Explanation: Fermenting cheese involves chemical reactions where bacteria convert lactose into lactic acid, producing new substances. This is a chemical change. Grating cheese, however, is a physical change because no new substances are formed.
- Answer: False

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11. Freezing water into ice cubes is a physical change.

- Explanation: Freezing water into ice cubes involves a change in state from liquid to solid. The chemical composition of water (H₂O) remains the same.
- Answer: True

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12. Iron rusting is a chemical change.

- Explanation: Iron rusting involves a chemical reaction between iron, oxygen, and water, forming iron oxide (rust). This is a chemical change because a new substance (rust) is formed.
- Answer: True

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Final Answers:

1. True
2. False
3. False
4. True
5. False
6. True
7. False
8. False
9. True
10. False
11. True
12. True

Final Answer:
\boxed{
\begin{array}{ll}
1. \text{True} & 7. \text{False} \\
2. \text{False} & 8. \text{False} \\
3. \text{False} & 9. \text{True} \\
4. \text{True} & 10. \text{False} \\
5. \text{False} & 11. \text{True} \\
6. \text{True} & 12. \text{True} \\
\end{array}
}