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Question
What is a physical change ? Give two examples of physical changes.
Solution
Physical change: These are changes in which no new substances are formed. These are temporary changes, which are easily reversible. The substance, which is involved in a physical change, does not lose its identity.
Examples:
- Water, if boiled, can be cooled and condensed.
- Mixing of iron fillings with sand is a physical change because they can be separated by a magnet.
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RELATED QUESTIONS
What role does energy play in initiating a chemical change ?
Photosynthesis cannot take place at night.
Which of the following are physical changes and which are chemical changes?
Burning of candle wax, Melting of candle wax, Mixing of iron filings and sand, Burning of wood, Breaking a piece of chalk, Burning a piece of paper, Cutting a piece of paper.
Which of the following are physical changes and which are chemical changes ?
Rusting of iron
Classify the following as a physical or a chemical change.
Boiling of water
What will you take into account while identifying the following?
A physical change in a substance.
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
Match the following
| Sr. No. | A | B | C |
| 1. | Melting | Change of state from liquid to solid | Ticking of clock |
| 2. | Condensation | Change of state from liquid to gas | Formation of ice cube |
| 3. | Evaporation | Change of state from solid to liquid | Collecting flowers |
| 4. | Freezing | Change of state from gas to liquid | Ice cube to water |
| 5. | Periodic change | Occurs at irregular time intervals | Water to steam |
| 6. | Non-periodic change | Occurs at regular time intervals | Steam to water drops |
Give two examples for each of the following cases:
Physical changes are reversible.
Iron pipes coated with zinc do not get rusted easily.
