Methods to Purify Water


 
 
Concept Explanation
 

Methods to Purify Water

Different Methods are used to make water safe for drinking.

1.  By Boiling: Water can be boiled for few minutes, to kill the germs present in it.

2.  By Filtration: Water can be passed through candle filters made of porcelain. Most of the bacteria are trapped in this way.

3.  By exposing water to UV Rays: An ultraviolet (UV) filter is fitted directly to the tap. Water from the tap passes through this filter. Ultraviolet light act on the water and kills the germs.

4.  By Treating with Chemicals: Potassium permanganate are put into the water. Potassium permanganate(KMnO_4) is a germicide. It kills the germs.

5.  If large amount of fluoride salt is present in water it is treated by lime. Excess fluoride in water causes defects in bones.

Municipal authorities remove all harmful constituents and make water safe for use before supplying to towns and cities. Chlorination is done by adding chlorine tablets or bleaching powder to the water. It kills disease germs.

Sample Questions
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Question : 1

Which of the following are correct :

(a) Ultraviolet light act on the water and kills the germs.

(b) Water can be boiled for few minutes, to kill the germs present in it.

(c) Potassium permanganate (KMnO_4) is a germicide. It kills the germs.

Right Option : D
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Question : 2

Which of the following is used to clean water in modern filters?

Right Option : C
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Question : 3

Which of the following method can be used to purify water ?

Right Option : D
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Explanation
 
 


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