Educational worksheet on physical and chemical changes featuring images and questions to identify types of changes.
A worksheet titled "Physical and Chemical Changes" with questions and images illustrating various changes such as glass breaking, burning wood, cutting meat, melting ice cubes, chopping wood, fireworks exploding, cooking an egg, boiling water, and rusting of iron.
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Step-by-step solution for: Physical and Chemical Changes (Worksheet) : Name: Surname: School ...
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Show Answer Key & Explanations
Step-by-step solution for: Physical and Chemical Changes (Worksheet) : Name: Surname: School ...
Here's the complete solution to the Physical and Chemical Changes Worksheet, with clear explanations for each question.
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A. Physical Change:
> A physical change is a change in which the substance’s physical properties (like shape, size, state of matter) are altered, but its chemical composition remains the same. No new substances are formed. These changes are often reversible.
*Examples:* Melting ice, cutting paper, dissolving sugar in water.
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B. Chemical Change:
> A chemical change is a process in which one or more substances are transformed into one or more different substances with new chemical properties. This involves breaking and forming chemical bonds. Usually irreversible and often accompanied by signs like color change, gas production, temperature change, or formation of a precipitate.
*Examples:* Burning wood, rusting iron, cooking an egg.
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1. F — A physical change causes the properties of a substance to change.
→ *False.* While physical changes may alter *physical properties* (like shape or state), they do NOT change the *chemical identity* or intrinsic properties (like reactivity or molecular structure). The substance remains chemically the same.
2. T — No new substance is formed with a physical change.
→ *True.* That’s the defining feature of a physical change — no new chemical substances are created.
3. F — A chemical change can be easily reversed.
→ *False.* Chemical changes are generally difficult or impossible to reverse without another chemical reaction. For example, you can’t “unburn” wood.
4. T — Changes in states of matter are physical changes.
→ *True.* Changing from solid to liquid (melting) or liquid to gas (boiling) doesn’t create a new substance — it’s just a rearrangement of molecules. Water is still H₂O whether solid, liquid, or gas.
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Answer: b) change in shape
→ *Explanation:*
- a) Change in temperature → Yes, exothermic/endothermic reactions release/absorb heat.
- c) Change in color → Often indicates new substances formed (e.g., rust turning iron reddish-brown).
- d) Formation of a gas → Bubbles or odor indicate gas production — a classic sign of chemical change.
- b) Change in shape → This is purely physical. Cutting, bending, or crushing something changes its shape but not its chemical identity.
✔ So, b) change in shape is NOT a sign of a chemical reaction.
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| Image / Description | Type of Change | Explanation |
|----------------------------|---------------------|-----------|
| Glass breaking | Physical | The glass shatters into pieces, but it’s still glass — no new substance formed. |
| Burning wood | Chemical | Wood turns into ash, smoke, and gases — new substances formed. Irreversible. |
| Cutting meat | Physical | You’re changing the size and shape, but the meat’s chemical makeup is unchanged. |
| Melting ice cubes | Physical | Solid water → liquid water. Same substance (H₂O), just different state. |
| Chopping wood | Physical | Like cutting meat — only shape/size changes. No chemical reaction. |
| Fireworks exploding | Chemical | Involves combustion and rapid chemical reactions producing light, sound, and new gases. |
| Cooking an egg | Chemical | Heat denatures proteins — irreversible change in structure and composition. |
| Boiling water | Physical | Liquid water → water vapor. Still H₂O. Only state changes. |
| Rusting of iron | Chemical | Iron reacts with oxygen and moisture to form iron oxide (rust) — new substance formed. |
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#### Q.1:
- Physical Change: Change in form or state without altering chemical identity.
- Chemical Change: Formation of new substances through chemical reactions.
#### Q.2:
1. F
2. T
3. F
4. T
#### Q.3:
b) change in shape
#### Q.4:
- Glass breaking → Physical
- Burning wood → Chemical
- Cutting meat → Physical
- Melting ice cubes → Physical
- Chopping wood → Physical
- Fireworks exploding → Chemical
- Cooking an egg → Chemical
- Boiling water → Physical
- Rusting of iron → Chemical
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Let me know if you’d like this formatted as a printable answer sheet!
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Q.1. Define the following terms:
A. Physical Change:
> A physical change is a change in which the substance’s physical properties (like shape, size, state of matter) are altered, but its chemical composition remains the same. No new substances are formed. These changes are often reversible.
*Examples:* Melting ice, cutting paper, dissolving sugar in water.
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B. Chemical Change:
> A chemical change is a process in which one or more substances are transformed into one or more different substances with new chemical properties. This involves breaking and forming chemical bonds. Usually irreversible and often accompanied by signs like color change, gas production, temperature change, or formation of a precipitate.
*Examples:* Burning wood, rusting iron, cooking an egg.
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Q.2. Write T or True if the statement is true; write F or False if the statement is false.
1. F — A physical change causes the properties of a substance to change.
→ *False.* While physical changes may alter *physical properties* (like shape or state), they do NOT change the *chemical identity* or intrinsic properties (like reactivity or molecular structure). The substance remains chemically the same.
2. T — No new substance is formed with a physical change.
→ *True.* That’s the defining feature of a physical change — no new chemical substances are created.
3. F — A chemical change can be easily reversed.
→ *False.* Chemical changes are generally difficult or impossible to reverse without another chemical reaction. For example, you can’t “unburn” wood.
4. T — Changes in states of matter are physical changes.
→ *True.* Changing from solid to liquid (melting) or liquid to gas (boiling) doesn’t create a new substance — it’s just a rearrangement of molecules. Water is still H₂O whether solid, liquid, or gas.
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Q.3. Which of the following is not a sign that a chemical reaction has occurred?
Answer: b) change in shape
→ *Explanation:*
- a) Change in temperature → Yes, exothermic/endothermic reactions release/absorb heat.
- c) Change in color → Often indicates new substances formed (e.g., rust turning iron reddish-brown).
- d) Formation of a gas → Bubbles or odor indicate gas production — a classic sign of chemical change.
- b) Change in shape → This is purely physical. Cutting, bending, or crushing something changes its shape but not its chemical identity.
✔ So, b) change in shape is NOT a sign of a chemical reaction.
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Q.4. Identify the following as physical change or chemical change.
| Image / Description | Type of Change | Explanation |
|----------------------------|---------------------|-----------|
| Glass breaking | Physical | The glass shatters into pieces, but it’s still glass — no new substance formed. |
| Burning wood | Chemical | Wood turns into ash, smoke, and gases — new substances formed. Irreversible. |
| Cutting meat | Physical | You’re changing the size and shape, but the meat’s chemical makeup is unchanged. |
| Melting ice cubes | Physical | Solid water → liquid water. Same substance (H₂O), just different state. |
| Chopping wood | Physical | Like cutting meat — only shape/size changes. No chemical reaction. |
| Fireworks exploding | Chemical | Involves combustion and rapid chemical reactions producing light, sound, and new gases. |
| Cooking an egg | Chemical | Heat denatures proteins — irreversible change in structure and composition. |
| Boiling water | Physical | Liquid water → water vapor. Still H₂O. Only state changes. |
| Rusting of iron | Chemical | Iron reacts with oxygen and moisture to form iron oxide (rust) — new substance formed. |
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✔ Final Answers Summary:
#### Q.1:
- Physical Change: Change in form or state without altering chemical identity.
- Chemical Change: Formation of new substances through chemical reactions.
#### Q.2:
1. F
2. T
3. F
4. T
#### Q.3:
b) change in shape
#### Q.4:
- Glass breaking → Physical
- Burning wood → Chemical
- Cutting meat → Physical
- Melting ice cubes → Physical
- Chopping wood → Physical
- Fireworks exploding → Chemical
- Cooking an egg → Chemical
- Boiling water → Physical
- Rusting of iron → Chemical
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