Worksheet assessing understanding of physical and chemical changes with true/false questions.

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 shape, size, state) 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 does not change.
- 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 create new compounds (e.g., caramelization). 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; it is simply a change in shape.
- 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, can usually be reversed by changing the conditions (e.g., cooling melted ice to freeze it again).
- 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, forming new substances. This is a chemical change. Grating cheese, however, is a physical change because it only alters the shape of the cheese without changing its chemical composition.
- Answer: False

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

- Explanation: Freezing water into ice cubes is 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, producing 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}
}