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प्रश्न
A girl is cooking some food in the kitchen. The smell of food being cooked soon reaches her brother's room. Explain how the smell could have reached her brother's room.
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उत्तर
The smell of food is reaching her brother’s room because the particles of matter are constantly moving from one place to another place, through the process 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.
Give a reason for the following observation.
Naphthalene balls disappear with time without leaving any solid.
State whether the following statement is true or false :
Red-brown bromine vapour diffuse into air in a gas jar but the colourless air molecules do not diffuse into bromine vapour.
Fill in the following blank with suitable words :
Solid, liquid and gas are the three ........................ of matter.
State two characteristic properties of a gas.
Give one example of diffusion of gases in a liquid.
Give reason for the following observation :
The smell of hot sizzling food reaches us even from a considerable distance but to get the smell from cold food, we have to go close to it.
When a gas jar full of air is placed upside down on a gas jar full of bromine vapours, the red-brown vapours of bromine from the lower jar go upward into the jar containing air. In this experiment :
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 ?
Comment upon the following:-
compressibility
