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प्रश्न
Explain the term vaporization.
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उत्तर
“Change of liquid to vapours (gas) on heating at constant temperature is called VAPORIZATION.”
When we heat a liquid, the temperature starts rising till it starts changing into vapours, and then the temperature remains constant for some time, though we are supplying heat. This heat supplied is being used to change every molecule of liquid into vapours and temperature does not rise till the whole of liquid is changed into vapours.
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संबंधित प्रश्न
Differentiate between melting point and boiling point, giving atleast one example of each.
Explain the terms boiling point.
A liquid can change into vapour state at a fixed temperature.
A certain quantity of water is heated from 20°C to 100°C. Its temperature is recorded after each 1 minute. The observations are:
| Time (in minute) | Temperature (in °C) |
| 0 | 20 |
| 1 | 30 |
| 2 | 40 |
| 3 | 50 |
| 4 | 60 |
| 5 | 70 |
| 6 | 80 |
| 7 | 90 |
| 8 | 100 |
| 9 | 100 |
| 10 | 100 |
| 11 | 100 |
| 12 | 100 |
It is difficult to cook vegetables on hills and mountains. Explain the reason.
The boiling point of water is defined as ______.
Boiling of egg results in ______ change.
A sample of water under study was found to boil at 102°C at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment.
Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.
Assertion (A): Burning of a candle is considered a physical as well as chemical change.
Reason (R): Melting of wax is a physical change melted wax turns into vapours and then bums which is a chemical change.
