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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
Select the correct alternative
The molecules can move freely anywhere in
- gases
- liquids
- solids
- none of the above
Solids have definite shape and definite volume.
Name the terms for the particles of matter which may or may not have independent existence.
The best evidence for the existence and movement of particles in liquids was provided by :
Which of the following substances are elements ?
Water, Salt, Mercury, Iron, Marble, Diamond, Wood, Nitrogen, Air, Graphite, Hydrogen, Oxygen, Sugar, Chlorine
What are the three general classes of matter ? Give one example of each type.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Define solvent.
Which of the following represents the solubility of sugar in water at 20°C ?
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Name the process which can be used to recover salt from an aqueous salt solution.
Which technique is used in a washing machine to squeeze out water from wet clothes while drying ?
How is scrap iron separated from a heap of waste materials in factories?
Which method is better for recovering sugar from sugar solution : evaporation or crystallisation ? Give reason
for your answer.
Explain how, nitrogen , oxygen and argon gases are separated from air.
One of the following does not undergo sublimation. This one is :
Tincture of iodine is a mixture of two materials X and Y. The material Y has a property that its solid form can be converted directly into vapours on heating by a process called Z.
- What could X be ?
- What could Y be ?
- Name the process Z.
- Which process would you use to recover both the components X and Y from tincture of iodine ?
- Which process can be used to recover only component Y from tincture of iodine ?
Define the term matter.
What type of matter glass is?
