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प्रश्न
No heat is supplied to a liquid during evaporation. How does then the liquid change into its vapours?
उत्तर
Due to the weak intermolecular force of attraction, the molecules of a liquid move freely inside it. In the process, they collide with each other transferring energy between them. Molecules with higher kinetic energy reach the surface of the liquid. These molecules absorb some more heat from the surroundings to gain sufficient kinetic energy to overcome the force of attraction on them due to other molecules inside the liquid escaping from the surface into space. These escaping molecules form the vapour of the liquid. Thus, evaporation of the liquid happens even though no heat is supplied to it.
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संबंधित प्रश्न
Boiling is a rapid phenomenon.
The molecules of liquid ............. heat from surroundings in evaporation.
Match the column
| Column A | Column B |
| (a) Blowing air increases | (1) Increase in intermolecular separation |
| (b) Increase in pressure increases | (2) Pendulum of a clock |
| (c) Thermal expansion |
(3) Cooking utensils |
| (d) Invar | (4) Boiling point |
| (e) Pyrex glass | (5) Evaporation |
In evaporation
The rate of evaporation of a liquid increases when:
The boiling point of a liquid is increased by
Comment on the statement ‘evaporation is a surface phenomenon’.
What is boiling? Explain it on the basis of molecular motion?
How is the heat energy supplied to a liquid used during boiling at a fixed temperature?
Name two ways of change of liquid state to the vapour state and distinguish them.
