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प्रश्न
State three differences between evaporation and boiling
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उत्तर
| BOILING | EVAPORATION | |
|---|---|---|
| Definition of these two terms | Boiling is vaporisation of liquid into gas due to continuous heating. Most of the time it is not a natural process. | Evaporation on the other hand is a natural process and it is similar to boiling , but the liquid form changes into gaseous form when there is a increase in either temperature or pressure or both. |
| Occurrance | Large mass | only on surface |
| Amount temperature involved | Boiling happens when the temperature reaches to the boiling point. | In Evaporation the temperature does not need to reach to boiling point |
| Bubble Formation | Bubble formation is visible | Bubbles do not form in evaporation |
| Energy | Usually external source of energy is needed for boiling to happen. | Most of the time energy for evaporation is supplied by the atmosphere or surrounding. |
| Length of the process | Rapid Process | Slow process compared to boiling |
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संबंधित प्रश्न
State whether the following is physical or chemical changes.
respiration in living beings —
Photosynthesis cannot take place at night.
Solve this crossword by using the clues that follow-
Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.
Down
1 . It is the change that takes place in case of swinging pendulum of a clock. –
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change.
Which of the following are physical changes and which are chemical changes?
Burning of candle wax, Melting of candle wax, Mixing of iron filings and sand, Burning of wood, Breaking a piece of chalk, Burning a piece of paper, Cutting a piece of paper.
The rusting of an iron object is called :
Give reasons why – separation of mixtures e.g. iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.
Name the following:
The type of change physical or chemical involved – ‘when a substance undergoes a change in state, colour or size’.
Select the correct answer from the choice given below to complete the sentence
The dissolution of lead nitrate in water is deemed as a _________ change.
Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and Step II are:
Fill in the blanks in the following statements using the words given in the box.
| rusted, colourful, substance, chemical, physical, reversible, iron oxide, object |
- Making sugar solution is a ______ change.
- A physical change is generally ______.
- Grinding of wheat grain changes its size. It is a ______ change.
- Iron benches kept in lawns and gardens get ______. It is a ______ change because a new ______ is formed.
