Q27 of 44 Page 14

Give some examples of Tyndall effect observed in your surroundings?

Tyndall effect is usually observed in colloids. It is called the light scattering by the particles in a colloid. It is named after the physicist John Tyndall. The other name is Tyndall scattering or Tyndall effect.


is observed in our surroundings when
(i) Sunlight passes through a heterogeneous mixture such as the canopy of a dense forest.
(ii) a fine beam of light enters a dark room through a small hole.


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25

Fill in the blanks.

(a) A colloid is a ——— mixture and its components can be separated by the technique known as ———.


(b) Ice, water and water vapour look different and display different —— properties but they are ——— the same.


(c) A mixture of chloroform and water taken in a separating funnel is mixed and left undisturbed for some time. The upper layer in the separating funnel will be of——— and the lower layer will be that of —


(d) A mixture of two or more miscible liquids, for which the difference in the boiling points is less than 25 K can be separated by the process called———.


(e) When light is passed through water containing a few drops of milk, it shows a bluish tinge. This is due to the ——— of light by milk and the phenomenon is called ———. This indicates that milk is a ——— solution.

 26

Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be a pure substance or a mixture? Give reasons for the same.

 28

Can we separate alcohol dissolved in water by using a separating funnel? If yes, then describe the procedure. If not, explain.

 29

On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.

(a) Is this a physical or a chemical change?


(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.