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प्रश्न
In a beam of sunlight entering a room, we can sometimes see dust particles moving in a haphazard way in the air. Why do these dust particles move?
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उत्तर
When a beam of sunlight enters a room, suspended dust particles are seen moving haphazardly. This is because the dust particles are constantly hit by the fast moving particles of air and due to this remain suspended despite gravity acting on them. This is an example of Brownian motion.
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संबंधित प्रश्न
The smallest unit of matter that exists freely in nature is called ...........
Fill in the blank :
The state of matter with definite volume and definite shape is called______
Name the scientist who studied the movement of pollen grains suspended in water through a microscope. What is this phenomenon known as?
When a crystal of potassium permanganate is placed at the bottom of water in a beaker, the water in the whole beaker turns purple on its own, even without stirring. This is an example of :
Which of the following is a mixture ?
Salt, Air, Water, Alum, Sugar
State one property in which a solution of sugar in water resembles a mixture of sugar and sand, and one property in which it differs from it.
Which of the following are not compounds ?
Chlorine gas, Potassium chloride, Iron powder, Iron sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond
What is meant by (i) elements (ii) compounds, and (iii) mixtures ?Write down the names of two elements, two compounds and two mixtures.
The element which is not common between the compounds called baking soda and soda ash is
Out of a colloid, solution and a suspension :
which one has the smallest particles ?
What is the effect of temperature on the solubility of solids in liquids ?
When the solid A is added to water, it dissolves with the evolution of a lot of heat and making little explosions to form two products B and C. The properties of products B and C are entirely different from those of solid A as well as water. Moreover, products B and C cannot be reconverted into solid A and water. When another solid D is added to water, it dissolves with the absorption of a little heat to form a product E which cools down. The product E shows the properties of both, solid D as well as water. Moreover, product E can be converted into solid D and water.
(a) What type of change occurs when solid A is dissolved in water ? Why ?
(b) What type of change occurs when solid D is dissolved in water ? Why ?
(c) Name a metal which you think could behave like solid A. Also name the products B and C.
(d) Name the solid D if it is the one which is used in making ordinary dry cells.
(e) Name the process by which D can be recovered from E.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Fill in the following blanks with suitable words :
The separation of liquids by fractional distillation is based on the difference in their .....................
Fill in the following blanks with suitable words :
The gases of air can be separated by fractional distillation of liquid air because they have different..............
Justify your answer.
| Figure 1 | Figure 2 | Figure 3 |
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The arrangement of particles in three different phases of matter is shown above.
- Which state is represented by Fig. 1?
- In which state will the inter-particle attraction be maximum?
- Which one of them cannot be contained in an open vessel?
- Which one can take the shape of its container?
Why wires cannot be drawn from materials such as stone or wood?
Rusting of an article made up of iron is called
Write scientific reason.
Lemon sherbat has sweet, sour and salty taste and it can be poured in a glass.
