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प्रश्न
Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
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उत्तर
- Wood cannot be joined again to form the original piece, but its properties do not change.
- This is a physical change. Wood cannot be restored to its original form after burning.
- Its properties also change, and heat is produced. This is a chemical change. Here, there are two different states of burning the wood and cutting it into small pieces.
- In this situation, two different types of changes are considered.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Passing of electric current through water, and water breaking down into hydrogen and oxygen gases.
Classify the following as chemical or physical change:
Dissolving common salt in water.
Which of the following are chemical changes?
- Growth of a plant
- Rusting of iron
- Mixing of iron fillings and sand
- Cooking of food
- Digestion of food
- Freezing of water
- Burning of candle
Classify the changes involved in the following process as physical or chemical changes:
Photosynthesis
Write true or false
Decomposition of leaves is a fast 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
Fill in the blank.
The reaction in which energy is evolved is called
State why addition of sodium chloride to water is considered a physical change, while addition of dilute sulphuric acid to zinc is considered a chemical change.
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
