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प्रश्न
Why does a lump of cotton wool shrink in water?
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उत्तर
A lump of cotton wool shrinks when immersed in water. This is because air present in the cotton wool escapes. Thus, the volume of the cotton wool decreases.
संबंधित प्रश्न
Define the term smog.
Write ‘True’ or ‘False’ in front of following statement.
Water containing dissolved carbon dioxide can dissolve marble.
What do you observe when Ice cold water is filled in a glass tumbler.
Fill in the blank
The reddish-brown powder on the surface of iron nails exposed to air and moisture is called _____.
What happens if the percentage of carbon-dioxide increases in the air?
______ is the percentage of nitrogen in air.
Match the following
| 1. | Moving Air | Photosynthesis |
| 2. | Layer in which we live | Troposphere |
| 3. | Stratosphere | Wind |
| 4. | Oxygen | Ozone layer |
| 5. | carbon-di-oxide | Combustion |
Arrange the following statements in correct sequence
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- Plants require energy for their growth.
- Plants take in oxygen and release carbon dioxide just as animals.
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- Such oxygen is available to animals and human beings for breathing.
- During this process, oxygen is released by plants.
Write just a few sentences for an imaginary situation if any of the following gases disappear from the atmosphere.
Oxygen
Write just a few sentences for an imaginary situation if any of the following gases disappear from the atmosphere.
Carbon dioxide
