ICSE Class 7 Chemistry
Question 2 of 13
Physical and Chemical Changes — Question 6
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Question Question 6
State three differences between evaporation and boiling.
| Evaporation | Boiling |
|---|---|
| Evaporation is a slow process. | Boiling is a fast process. |
| It takes place from the surface of the liquid. | Evaporation takes place from all parts of the liquid during boiling. |
| It takes place at all temperatures below its boiling point. | It takes place at a fixed temperature i.e. at its boiling point. |
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