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प्रश्न
Why is cooling produced on evaporation of a liquid?
उत्तर
For evaporation of a liquid, it requires HEAT. This heat is taken from the surroundings like body or palm or forehead or finger and its temperature falls and we feel cool.
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संबंधित प्रश्न
Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Evaporation takes place from the
What is evaporation?
Water in a dish evaporates faster than in a bottle. Give reason.
A patient suffering from high fever is advised to put wet clot strips on his forehead. Why?
Why does all the water of the earth not get evaporated during hot summer days ?
During summer days, water kept in an earthen pot (pitcher) becomes cool because of the phenomenon of :
The scientists now say that there are actually five states of matter A, B, C, D and E. The state A has a fixed volume but no fixed shape. The state B can be compressed very easily by applying pressure and state C has a fixed shape as well as a fixed volume. The state D is a mixture of free electrons and ions whereas state E is named after an Indian scientist and a famous physicist.
- Name the physical states (i) A (ii) B (iii) C (iv) D, and (v) E
- Name one substance belonging to state C which can directly change into vapours on heating. What is this process known as ?
- Name one substance which normally belongs to state B but whose solid form changes directly into gaseous state.
- Name the most common substance belonging to state A.
- Which state of matter makes the sun and other stars to glow ?
Evaporation is a fast process and occurs only at the surface of the liquid.
The rate of evaporation is more when the surface area is greater.
