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प्रश्न
What do you observe when :
a piece of paper is burnt
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उत्तर
On burning piece of paper produces carbon dioxide and ash is left behind. Is a chemical change.
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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
State whether the following is physical or chemical changes.
burning of wood -
State whether the following is physical or chemical changes.
Melting of wax —
State whether the following is physical or chemical changes.
Boiling of an egg —
True or false?
In a chemical change, rearrangement of molecules and atoms involves some energy changes.
What role does energy play in initiating a chemical change ?
Give reason.
While purchasing canned food, its expiry date should be checked.
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 |
