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प्रश्न
Give the main differences between physical changes and chemical changes.
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उत्तर
Important differences between a physical and a chemical change are given below:
| PHYSIAL CHANGE | CHEMICAL CHANGE |
| 1. No new substance is formed. | 1. A new substance is formed. |
| 2. Physical change is reversible. | 2. Chemical change is usually irreversible. |
| 3. It is a temporary change. | 3. It is a permanent change. |
| 4. No heat energy is evolved or absorbed. | 4. Heat energy is evolved or consumed in a large amount. |
| 5. Examples: Melting of ice, formation of clouds, tearing of cloth etc. | 5. Examples: Rusting of iron, ripening of fruits, cooking of food etc. |
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संबंधित प्रश्न
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
What are man-made changes ?
Classify the following as physical or chemical changes :
- Cooking of food
- Boiling of water
- Cutting of trees
- D0issolving salt in water
- Digestion of food
- Melting of ice
Separate the following into physical and chemical changes :
Sublimation of a solid, Decomposition of water into hydrogen and oxygen by passing electric current, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water
Classify the following as a physical or a chemical change.
Melting of wax
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Differentiate between the following change with a suitable example.
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Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
Mention a few physical properties of a substance.
Mention some of the different conditions needed for chemical changes to occur.
