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प्रश्न
Comment on the statement ‘evaporation is a surface phenomenon’.
उत्तर
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Particles at the Surface Escape:
- In a liquid, particles at the surface are loosely bound compared to those inside.
- When surface particles gain enough energy (e.g., from heat), they overcome the forces of attraction and escape into the air as vapor.
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No Boiling Required:
- Unlike boiling, evaporation happens at any temperature below the boiling point and does not require heating the entire liquid.
- Only the particles at the surface participate in evaporation.
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Examples:
- Water in a glass slowly evaporates from the surface over time.
- Sweat on the skin evaporates, cooling the body.
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संबंधित प्रश्न
Evaporation is rapid on a wet day.
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 |
The boiling point of a liquid is increased by
Do all the molecules of a liquid take part in evaporation? If not, explain your answer.
Give reason for the increase in rate of evaporation of a liquid when surface area of liquid is increased.
Give reason for the increase in the rate of evaporation of a liquid when temperature of liquid is increased.
What is boiling? Explain it on the basis of molecular motion?
What is the change in average kinetic energy of molecules of a liquid during boiling at its boiling point?
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.
