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प्रश्न
Explain how, the smell of food being cooked in the kitchen reaches us even from a considerable distance.
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उत्तर
The smell of food cooked in the kitchen reaches us even from a considerable distance because the tiny particles of the vapour of food mix with the air and move continuously in all directions. This process is called diffusion.
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संबंधित प्रश्न
The mass per unit volume of a substance is called density.
(density = mass/volume).
Arrange the following in order of increasing density-
air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Name two gases which are supplied in compressed form in homes and hospitals.
When an incense stick (agarbatti) is lighted in one corner of a room, its fragrance quickly spreads in the entire room. Name the process involved in this.
Name two gases of air which dissolve in water by diffusion. What is the importance of this process in nature?
The substance X normally exists in a physical state which can flow easily but does not fill its vessel completely. It also turns anhydrous copper sulphate blue. When substance X is cooled excessively, it changes into a substance Y which has a fixed shape as well as a fixed volume. If, however, the substance X is heated strongly, it changes into a substance Z which has neither a fixed shape nor a fixed volume.
- Name the substances (i) X (ii) Y and (iii) Z.
- What is the process of conversion of X into Y known as ?
- At which temperature X gets converted into Y ?
- What is the process of conversion of X into Z known as ?
- At which temperature X gets converted into Z ?
Why do gases not have fixed shape?
Comment upon the following:-
rigidity
Which of the following is false for gases?
Explain why?
- A gas fills a vessel completely?
- Camphor disappears without leaving any residue.
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| Fig. I | Fig. II |
In figure-I, an air column of length ℓ1 is entrapped by a column of Hg of length 8 cm. In figure-II length of same air column at the same temperature is ℓ2. The `ℓ_1/ℓ_2` is:
(1 atm = 76 cm of Hg)
