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Inspite of using chlorine tablets, the drinking water was declared unsafe. What could be four possible reasons for this?
(i) Chlorination destroys bacteria but does not remove the suspended impurities.
(ii) Excess use of chlorine can damage circulatory system and respiratory system. Excess chlorine reacts with water in your digestive tract to form hydrochloric acid and hydrochlorous acid. Both acids are poisonous to humans.
(iii) The ratio of chlorine and water was not correct.
(iv) Tablet not dissolved completely.
For purifying her drinking water, Geeta has to buy either reverse osmosis filter or an ordinary electric filter. Help her take a decision by giving her all the necessary information she would require about these filters.
| Electric filter | Reverse Osmosis | |
| (i) | Take care of suspended particles. | It has sediment filter which removes suspended particles. |
| (ii) | Carbon granules remove chemical impurities. | The activated carbon filters remove chemical and enhance the taste. |
| (iii) | Ultraviolet light kills germs and microorganisms. | Semi-permeable membrane removes lead, arsenic etc. |
| (iv) | Not able to remove e-coli virus. | Remove all e-coli virus. |
| (v) | Cheaper | Expensive |
| (vi) | Works well in soft water | Can work any type of water |
| (vii) | Filter gets changed every six months | Filter needs to be changed once in a year. |
| (ix) | Easy to maintain & no wastage of water. | Wastage of water. |
People of Basra village use alum to make their water potable. Convince them to use chlorine tablets instead. Tell them about the procedure to use these tablets, two advantages of using the tablets and two precautions while using them.
Method:
Advantages of using chlorine:
Precautions:
During rainy season almost everyone in a specific locality suffers from stomach ailments. You have suggested them to use chlorine tablets to make water safer for drinking. Write the method and give two reasons for your suggestion. Also, write two precautionary measures while using these tablets.
| Method | Reasons | Precautions |
| One tablet of 4 mg is dissolved in 1 litre of water. | It kills coliform bacteria. | Keep in a dry place. |
| Shaken well, left for 10 minutes before consuming. | It is easy to use. | Should not be expired. |
| It is hassle-free. | If water dirtier use 2 tablets and wait for 20 minutes before using. |
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