CBSE Class 10 Science 2019 Outside Delhi Set 1

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Question : 15
Total: 27
Write the essential function performed by ozone at the higher levels of the Earth's atmosphere ? How is it produced? Name the synthetic chemicals mainly responsible for the drop of amount of ozone in the atmosphere. How can the use of these chemicals be reduced?
Solution:  
Ozone layer absorbs most of the harmful ultraviolet radiations from the sun to the earth. It is formed high up in the atmosphere by the action of ultraviolet radiation on oxygen gas. Chlorofluorocarbons are the synthetic chemicals responsible for the drop of amount of ozone in the atmosphere.
O2
UV
O
+O

O+O2O3
The use of these chemicals can be reduced by :
(i) Replacement of chloroflurocarbons with hydrochlorofluorocarbons because it breaks down more quickly.
(ii) Safe disposal of old appliances such as refrigerators and freezers.
(iii) Finding substitute chemicals that are ozone friendly.
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