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प्रश्न
Give a reason why rusting of iron is a chemical change but, the magnetization of iron is a physical change.
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उत्तर
Rusting of iron is a chemical change, as composition changes, the reddish-brown flaky powder is formed with new properties and is an irreversible, permanent change, but magnetization of iron is a temporary and reversible change with no change in composition and is a physical change.
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संबंधित प्रश्न
Match the columns
| column A | coulmn B |
| 1. A change which cannot be easily reversed | a. man-made change |
| 2.A change that repeats itself at regular intervals | b. chemical change |
| 3. A change that is made by humans | c. physical change |
|
4. A change in which the original substance cannot be obtained |
d. periodic change |
| 5. A change where no new substance is formade | e. irreversible change |
| f. slow change |
Write short answer.
Give two examples of periodic changes
What role does energy play in initiating a chemical change ?
Classify the following as a physical or a chemical change.
Manufacture of salt from sea water
Classify the following as a physical or a chemical change.
Burning of paper
Name the following:
The final product of the physical change involved during the ‘melting of a piece of wax’.
Compare the energy changes involved during a physical and a chemical change.
State which of the following 1 to 5 pertain to – A: Physical Change B: Chemical change :
- Sublimation.
- Fermentation.
- Liquefaction or condensation.
- Magnetization.
- Respiration.
When solute is dissolved in a solvent it forms a solution.
Match the items of Column I with the items of Column II.
| Column I | Column II | ||
| (a) | Large crystals | (i) | Turns lime water into milky |
| (b) | Depositing a layer of zinc on iron | (ii) | Physical change |
| (c) | Souring of milk | (iii) | Rust |
| (d) | Carbon dioxide | (iv) | Sugar candy (Mishri) |
| (e) | Iron oxide | (v) | Chemical change |
| (f) | Dissolving common salt in water | (vi) | Galvanisation |
