ICSE Class 7 Chemistry
Question 3 of 13
Physical and Chemical Changes — Question 7
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Question Question 7
State four differences between physical and chemical changes.
| Physical changes | Chemical changes |
|---|---|
| Change is temporary. | Change is permanent. |
| No new substance is formed. There is change only in physical properties. | New substances are formed with entirely different properties. |
| Change can be reversed by simple methods. | Change cannot be reversed by simple methods. |
| Heat or light may or may not be given out or consumed. | Heat or light or both are given out or consumed. |
ICSE Class VII Chemistry Chapter 2 12 Marks
Physical and Chemical Changes — Quick Study Guide
Changes around us are classified as physical (no new substance formed) or chemical (new substance formed). Understanding the difference is fundamental to chemistry.
Key Definitions
- Physical change: No new substance formed, usually reversible (e.g., melting ice, dissolving sugar)
- Chemical change: New substance formed, usually irreversible (e.g., burning, rusting, cooking)
- Exothermic: Reaction that releases heat (e.g., burning fuel)
- Endothermic: Reaction that absorbs heat (e.g., photosynthesis)
Six Signs of Chemical Change
Colour change, gas evolution, temperature change, precipitate formation, smell change, light/sound emission.
Exam Tips
- Burning a candle = BOTH physical and chemical change
- Dissolving salt/sugar in water = physical change (recoverable)
- Not all physical changes are reversible (tearing paper)
- Learn the comparison table (6 differences) thoroughly
Bright Tutorials | ICSE Class VII Chemistry | Chapter 2: Physical and Chemical Changes | Contact: 9403781999