Question of 20
Q.Define the following terms:
(a) Freons
(b) BOD
(c) Green house effect
Kerala DhseKerala DHSE Plus One Board 2020Subjective· 3mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →Three environmental-chemistry definitions: Freons (CFCs, ozone depletion), BOD (organic water pollution indicator), and the greenhouse effect (atmospheric heat trapping).
- Freons Chlorofluorocarbon (CFC) compounds — organic compounds of carbon containing chlorine and fluorine (e.g. CFCl3, CF2Cl2) — widely used as refrigerants and aerosol propellants. They are chemically inert and non-toxic in the lower atmosphere, but on diffusing into the stratosphere they are broken down by UV light to release chlorine free radicals that catalytically destroy ozone, causing depletion of the ozone layer.
- BOD (Biochemical/Biological Oxygen Demand) The amount of dissolved oxygen (in mg/L or ppm) required by microorganisms/bacteria to biologically decompose the organic matter present in a given volume of a water sample, usually measured over 5 days at 20°C. It is used to indicate the degree of organic pollution of water: clean water has a BOD below about 5 ppm, while highly polluted water has a much higher BOD (17 ppm or more).
- Green house effect …
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