1. After a rain,why does the water on the ground dry up?
What is evaporation?
After a rain,why does the water on the ground dry up?
The water evaporates.
Evaporation - A process in which a liquid changes to gas at temperature below its boiling point.

2. What are the similarities and differences between evaporation and boiling?
Both are process in which a substance changes from liquid to gas.
Both involve latent heat of vaporization.

3. takes place at any temperature takes place only at boiling point
Differences:
Evaporation
Boiling
takes place at any temperature
takes place only at boiling point
takes place only on the surface of a liquid
takes place within a liquid and on its surface
bubble

4. Why do we feel cold when we leave the water after bathing?
Cooling by evaporation
Why do we feel cold when we leave the water after bathing?
It is due to the cooling effect of evaporation.
Latent heat of vaporization is taken away from our body when the water on our skin evaporates.

5. Daily examples of cooling by evaporation
Our sweat glands give out sweat during exercise.
Sweat evaporates and cools our body.
Dogs cool themselves by evaporation of moisture from their tongues.

6. Warming by condensation
In winter, why do we feel warmer when we stay in the shower stall after taking a shower?
Condensation of vapour on our skin releases latent heat of vaporization.

7. How is the fish cooked by steam?
Steam releases a large amount of energy when it condenses on the fish.

8. Under what conditions do the wet clothes dry faster by evaporation?
Factors affecting the rate of evaporation
Under what conditions do the wet clothes dry faster by evaporation?

9. The rate of evaporation can be increased by:
high temperature
low humidity
presence of wind
increasing surface area

10. Which cloth will dry faster? Why?
The red one.
It has a larger exposed surface area.

11. Microscopic interpretation of evaporation
EXTENSION
As a result of collisions, some molecules gain enough kinetic energy to escape from the liquid surface.
The liquid cools down.
In a liquid, different molecules have different kinetic energy and different speeds.
Molecules with less kinetic energy remain in the liquid.
Video: Microscopic interpretation of evaporation

12. That’s the end of Section 4.4
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