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प्रश्न
Given reason:
Freezing of water to ice and evaporation of water are physical changes.
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उत्तर
Freezing of water to ice and evaporation of water are physical change because water can be brought back to its original (liquid) form by
- We can heat the ice to bring it back to water.
- We can cool down the vapours to bring it back to water.
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संबंधित प्रश्न
Name a chemical change which takes place in presence of:
Tick (√) the correct alternative from the choice given for the following statement
Which one of the following is volatile in nature ?
Classify the following as a physical or a chemical change.
Boiling of water
Fill in the blank.
The reaction in which energy is evolved is called
Photosynthesis is a natural process by which green plants manufacture food in the presence of sunlight.
State the conclusions which can be drawn, to represent photosynthesis as a physical or 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. |
Name the following:
The final product of the physical change involved during the ‘melting of a piece of wax’.
Give the reason why the following is considered as chemical changes.
Copper carbonate on heat gives copper oxide and carbon dioxide.
Name the following.
A form of energy required for a chemical change.
Cutting a log of wood into pieces is a chemical change.
