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प्रश्न
Chemical changes are accompanied by changes in energy.
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उत्तर
In a chemical change, molecules and atoms rearrange themselves to form new substances. This rearrangement involves some energy changes. It can either be absorption or evolution of energy.
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संबंधित प्रश्न
What do you observe when :
solid ammonium chloride is heated
State whether the following is physical or chemical changes.
passing electric current through a heater rod —
State whether the following is physical or chemical changes.
Melting of wax —
Tick (√) the correct alternative from the choice given for the following statement
When sugar is heated, its colour changes into
Distinguish between the following.
Periodic change and non-periodic change
Under which different types can the following changes be classified?
Stretching of a spring.
Fill in the blanks with the appropriate words of the statement given below:
Chemical changes may involve exchange of energy in the form of __________ and _________.
Observe the picture containing a kettle and note that it has salt water in it and answer the following questions:
- What is name of the process that is done to the kettle?
- What will happen to the content of the kettle?
- What kind of change is occurring on the cold surface of the metal plate?
- What can you say about the quality of water that is obtained in the beaker?
Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
| S. No. | Change | Can be reversed (Yes/No) |
| 1. | The sawing of a piece of wood | |
| 2. | The melting of ice candy | |
| 3. | Dissolving sugar in water | |
| 4. | The cooking of food | |
| 5. | The ripening of a mango | |
| 6. | Souring of milk |
What is the change?
