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प्रश्न
Explain with an example to demonstrates that when a liquid evaporates, it takes heat from its surroundings.
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उत्तर
If some spirit is poured on cotton wrapped around the bulb of a thermometer, the reading of the thermometer falls. This shows that cooling is produced when a liquid evaporates taking heat from surroundings.
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संबंधित प्रश्न
Evaporation takes place from the
State three factors which affect the rate of evaporation of a liquid.
Wet clothes dry more quickly on a warm dry day than on a cold humid day. Explain.
Why is cooling produced on evaporation of a liquid?
A patient suffering from high fever is advised to put wet clot strips on his forehead. Why?
If the back of your hand is moistened with alcohol, you will find that it rapidly becomes dry. Why is it that while it is drying, your hand feels cool ?
What type of clothes should we wear in summer ? Why ?
Why does evaporation cool a liquid ?
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 ?
Comment on the following statements:
Rate of evaporation of an aqueous solution decreases with increase in humidity.
