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प्रश्न
Give some examples of the Tyndall effect observed in your surroundings?
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उत्तर
Examples of the Tyndall effect:
- When light rays enter into a dark room through a hole or a small window.
- Sunlight passes through a group of trees in the forest.
- Path of light rays seen in front of the projector in a cinema hall.
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संबंधित प्रश्न
What are the two conditions for the interconversion of states of matter ?
Write true or false for each statement. Rewrite the false statement correctly.
Matter cannot exist in different states.
What are the conditions for 'something' to be called 'matter'?
Name two processes which provide the best evidence for the motion of particles in matter.
When a crystal of potassium permanganate is placed in a beaker, its purple colour spreads throughout the water. What does this observation tell us about the nature of potassium permanganate and water?
Explain why, osmosis can be considered to be a special kind of diffusion. Classify the following into
(i) osmosis, and (ii) diffusion :
- swelling up of a raisin on keeping in water
- spreading of virus on sneezing
- earthworm dying on coming in contact with common salt
- shrinking of grapes kept in thick sugar syrup
- preserving of pickles in salt
- spreading of smell of cake being baked in the kitchen
- aquatic animals using oxygen dissolved in water during respiration
State any two properties for believing that aluminium is a metal.
Name a metal which is yellow in colour.
What are the three general classes of matter ? Give one example of each type.
One of the following substances is neither a good conductor of electricity nor an insulator. This substance is :
A, B and C are all liquids. Liquid A has a comparatively low boiling point. On heating, liquid A vaporises completely without leaving behind any residue. Liquid A is being used increasingly as a fuel in motor vehicles either alone or by mixing with petrol. Liquid B has a very high boiling point. It also vaporises completely on heating, without leaving any residue. Liquid B is a conductor of electricity and used in making thermometers. Liquid C has a moderate boiling point. On heating, liquid C vaporises leaving behind a white solid D which is used in cooking vegetables. The condensation of vapours from C give a liquid E which turns anhydrous CuSO4 to blue.
(a) Which liquid could be an element ? Name this element.
(b) Which liquid could be a mixture ? Name this mixture.
(c) Which liquid could be a compound ? Name this compound.
(d) What could the solid D be ?
(e) What do you think is liquid E ?
Classify the following into true solutions and colloidal solutions:
Ink, Salt solution, Starch solution, Blood, Sugar solution
9.72 g of potassium chloride dissolves in 30 g of water at 70°C. Calculate the solubility of potassium chloride at that temperature.
What do you understand by the statement " the solubility of copper sulphate in water at 20°C is 20.7 g" ?
Name the process which is used in milk dairies to separate cream from milk.
How will you separate a mixture of common salt, sulphur powder and sand ?
Explain how, nitrogen , oxygen and argon gases are separated from air.
Pure copper sulphate can be obtained from an impure sample by the process of :
A solid mixture contains four constituents P, Q, R and S. P consists of tiny grains and it is mixed with
cement for plastering the walls. Q is a white solid which is recovered on a large scale from sea water by the
process of evaporation. R is in the form of tiny particles of a material whose corrosion is called rusting. And
S is a white solid which is used in making ordinary dry cells.
- What could P, Q, R and S be ?
- How would you separate a mixture containing P, Q, R and S ?
Which of the following statements are true for pure substances?
(i) Pure substances contain only one kind of particles
(ii) Pure substances may be compounds or mixtures
(iii) Pure substances have the same composition throughout
(iv) Pure substances can be exemplified by all elements other than nickel
