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प्रश्न
Define the following term Freezing.
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उत्तर
Freezing : It is a process in which a liquid changes into a solid on cooling.
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संबंधित प्रश्न
Water in a dish evaporates faster than in a bottle. Give reason.
Explain with an example to demonstrates that when a liquid evaporates, it takes heat from its surroundings.
Explain why in hot summer days water remains cool in earthen pots.
Why is heat energy needed to melt a solid ? What is this heat energy called ?
What type of clothes should we wear in summer ? Why ?
How will you demonstrate that water vapour is present in air ?
What is evaporation ? State the various factors which affect evaporation.
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:
Evaporation produces cooling.
Evaporation is a fast process and occurs only at the surface of the liquid.
