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प्रश्न
What role does energy play in initiating a chemical change ?
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उत्तर
In a chemical change molecules and atoms rearrange themselves to form new substances. This process involves some energy changes. In some changes energy is absorbed
e. g. burning of a substance and in some cases energy is evolved e.g. photosynthesis
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संबंधित प्रश्न
What do you observe when :
solid ammonium chloride is heated
What do you observe when :
a spoon of sugar is heated in a pan
Fill in the blank
Burning of fuel is a _______ change.
State whether the following is physical or chemical changes.
passing electric current through a heater rod —
True or false?
During a physical change energy is either given out or absorbed by the system.
Chemical changes are accompanied by changes in energy.
Distinguish between the following.
Periodic change and non-periodic change
Under which different types can the following changes be classified?
Conversion of milk into yoghurt.
Give reason.
While purchasing canned food, its expiry date should be checked.
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 |
