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प्रश्न
Give a reason for the following observation.
We can get the smell of perfume sitting several metres away.
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उत्तर
Perfume is also a volatile liquid. It immediately turns into vapour and diffuses into the air, which is why we can smell it even if we are sitting far away. This phenomenon occurs as a result of 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.
Arrange the following substances in increasing order of forces of attraction between particles -
water, sugar, oxygen
Name two gases which are supplied in compressed form in homes and hospitals.
State two characteristic properties of a gas.
Explain why, when a bottle of perfume is opened in a room, we can smell it even from a considerable distance.
A substance has neither a fixed shape nor a fixed volume. State whether it is a solid, a liquid or a gas.
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:-
compressibility
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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)
