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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
What type of clothes should we wear in summer?
State three factors which affect the rate of evaporation of a liquid.
Water in a dish evaporates faster than in a bottle. Give reason.
Explain why in hot summer days water remains cool in earthen pots.
Which produces more severe burns : boiling water or steam ? 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 ?
Why does evaporation cool a liquid ?
During summer days, water kept in an earthen pot (pitcher) becomes cool because of the phenomenon of :
The evaporation of water increases under the following conditions :
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 ?
