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प्रश्न
What are molecules?
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उत्तर
Molecules are the smallest unit of matter. They exhibit all the properties of that kind of matter and is capable of independent existence.
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संबंधित प्रश्न
Explain why, the diffusion of a solid in another solid is a very slow process.
Give reasons:
When a teaspoon of sugar is added to half a glass of water and stirred, the water level in the glass remains unchanged.
Describe simple experiments to prove that gases occupy space.
Describe simple experiments to prove that gases have mass.
Complete the statement given below by selecting the correct word.
Solids and liquids have a definite ____ but gases do not.
State the property of the following substance.
The melting point of ice is 0°C.
Filtration method is effective in separating ______ mixture.
Complete the given analogy.
Large Inter-particle space: Gas:: ______ :solid.
Match the following.
| Srl. no. | A | B | C |
| i | Separation of visible undesirable components | Water mixed with chalk powder | Magnetic Separation |
| ii | Separation of heavier and lighter components | Sand and water | Decantation |
| iii | Separation of insoluble impurities | Iron impurities | Filtration |
| iv | Separation of magnetic components from non-magnetic components | Rice and stone | Hand-picking |
| v | Separation of solids from liquids | Husk and paddy | Winnowing |
A strong current of trivalent gaseous boron passed through a silicon crystal decreases the density of the crystal due to part replacement of silicon by boron and due to interstitial vacancies created by missing Si atoms. In one such experiment, one gram of silicon is taken and the boron atoms are found to be 1000 ppm by weight, when the density of the Si crystal decreases by 12%. The percentage of missing vacancies due to silicon, which are filled up by boron atoms will be ____ g. [Given · Atomic wt. Si= 30, B = 11]
