Advertisements
Advertisements
Question
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?
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
Define the following term of Atom .
What is the general name of the materials which contain at least two pure substances and show the properties
of their constituents ?
How would you confirm that a colourless liquid given to your is pure water ?
Name a metal which has no fixed shape.
State whether colloidal solutions are homogeneous or heterogeneous.
Explain what happens when a beam of light is passed through a colloidal solution.
Explain what happens when a beam of light is passed through a colloidal solution.
Which of the following do not exhibit Tyndall effect ?
Starch solution, Sugar solution, Ink, Salt solution, Copper sulphate solution, Ammonium chloride solution, Fog, Smoke, Car exhausts.
One of the following is a solid foam. This one is :
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Write a method to separate a mixture of sand and potash alum.
How would you obtain sodium chloride from a mixture of sodium chloride and sulphur without using water ?
How is scrap iron separated from a heap of waste materials in factories?
How will you separate camphor, common salt and iron nails from their mixture ?
The material which is added to water during purification process at the water works so as to disinfect it is :
Naphthalene can be separated from sand :
Explain the meaning of the term matter with special reference to the term ‘substance’.
Asmita went to buy an earthen pot. There she saw many things kept for sale.
How did she identify what she needed?
The non S I and S I units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity:
| (A) | (B) | ||
| (a) | degree celsius | (i) | kilogram |
| (b) | centimetre | (ii) | pascal |
| (c) | gram per centimetre cube | (iii) | metre |
| (d) | bar | (iv) | kelvin |
| (e) | milligram | (v) | kilogram per metre cube |
Define the term matter.
