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प्रश्न
Why are we able to sip hot tea or milk faster from a saucer rather than from a cup ?
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उत्तर
We are able to sip hot tea or milk faster from a saucer rather than from a cup because saucer has a larger surface area due to which evaporation occurs faster. The vapours take up the latent heat from hot milk or tea kept in the saucer faster, than in a cup which has a smaller surface area than the saucer and make the contents of the saucer cool down faster.
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संबंधित प्रश्न
Why are we able to sip hot tea or milk faster from a saucer than a cup?
What produces more severe burns, boiling water or steam?
What is evaporation?
Explain with an example to demonstrates that when a liquid evaporates, it takes heat from its surroundings.
Give two applications of evaporation.
Explain why in hot summer days water remains cool in earthen pots.
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 ?
Look at Fig. 1.3 and suggest in which of the vessels A,B, C or D the rate of evaporation will be the highest? Explain.
Comment on the following statements:
Rate of evaporation of an aqueous solution decreases with increase in humidity.
