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प्रश्न
Why does our palm feel cold when we put some acetone (or perfume) on it ?
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उत्तर
Our palm feels cool when we put acetone over it because acetone takes up the latent heat of vaporisation to change into vapour from our palm.
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संबंधित प्रश्न
Why is cooling produced on evaporation of a liquid?
Explain with an example to demonstrates that when a liquid evaporates, it takes heat from its surroundings.
Why is heat energy needed to melt a solid ? What is this heat energy called ?
Why does all the water of the earth not get evaporated during hot summer days ?
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 ?
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 ?
Give a geographical reason:
Air becomes saturated.
How does the water kept in an earthen pot remain cool?
Evaporation of water from lakes and river ______.
The rate of evaporation is more when the surface area is greater.
