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प्रश्न
When can you say a material is waterproof material?
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उत्तर
Materials that do not allow water to pass through them are called waterproof materials.
Example: raincoat, aluminium foil of tablet strip.
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संबंधित प्रश्न
We cannot compress, cut or bend the rough materials easily.
Sand paper is a good example for smooth materials.
Test the flexibility.
Give one plastic scale and a wooden scale to the students. Ask them to bend. Tabulate their observation (bends, does not bend).
| Plastic Scale | Wooden Scale |
| ______ | ______ |
Sugar does not dissolve in water.
Choose the odd one:
Smooth materials do not have ups and downs.
Paheli prepared a blue coloured solution of copper sulphate in beaker A and placed an iron nail in it. Boojho prepared a yellowish green solution of ferrous sulphate in beaker B and placed a copper wire in it. What changes will they observe in the two beakers after an hour?
Match the substances in Column A with their applications given in Column B.
|
Column A |
Column B |
| (a) oxygen | (i) for making crackers |
| (b) copper | (ii) for disinfecting water |
| (c) sulphur | (iii) all living beings inhale during breathing |
| (d) iron | (iv) for making electric wires |
| (e) chlorine | (v) for making rails |
Pick one material from the following which is completely soluble in water.
Which of the following materials is not lustrous?
