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प्रश्न
Give reason.
A dry handkerchief gets wet at once on dipping in water, but it takes longer for a wet handkerchief to dry.
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उत्तर
A dry handkerchief gets wet at once because it quickly absorbs the water in which it is dipped. However, it takes longer for a wet handkerchief to dry because the water needs to evaporate from the handkerchief. Evaporation is a slow process that is dependent on other factors as well, like relative humidity.
संबंधित प्रश्न
State whether the following is physical or chemical changes.
burning of wood -
State whether the following is physical or chemical changes.
Melting of wax —
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 ?
Under which different types can the following changes be classified?
Occurrence of an earthquake.
Fill in the blank with the correct word of the statement given below:
Ammonium chloride, a sublimable solid undergoes _________ on heating.
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 |
______ is the process in which something becomes different from what it was earlier.
What is the change?
