Key Points
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Element
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Description
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CFC
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- Ozone gas is continuously formed by the action of UV rays on molecular oxygen.
- It is also degraded into molecular oxygen in the stratosphere.
- There should be a balance between the production and degradation of ozone in the stratosphere.
- Of late, the balance has been disrupted due to the enhancement of ozone-depleting substances (ODS).
- The main ingredient of any ODS is the presence of a halogen molecule.
- In the stratosphere, UV rays act on them releasing the halogen atoms.
- For example, in CFCs, Cl degrades ozone, releasing molecular oxygen.
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CO2
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- An increase in the average temperature of the earth's surface due to the greenhouse effect is called global warming.
- Global Warming refers to a slow rise in the average temperature of the earth.
- The main reason for global warming is an exaggerated Greenhouse effect.
- Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Sulphur hexafluoride (SF6), Hydrofluorocarbons (HFC), Perfluorocarbons (PFC) are major Greenhouse gases.
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BOD
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- Water pollution by organic wastes is measured in terms of Biochemical Oxygen Demand (BOD).
- BOD is the amount of dissolved oxygen needed by bacteria in decomposing the organic wastes present in water.
- The higher value of BOD indicates low dissolved oxygen content of water and high water pollution.
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MIC
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- The Bhopal disaster, also referred to as the Bhopal gas tragedy.
- It was a Methyl Iso cyanide (MIC) gas leak incident on the night of 2–3 December 1984 at the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh, India.
- It is considered among the world's worst industrial disasters.
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Thus, the correct match is A (III), B (II), C (IV), D (I)
| List I |
List II |
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A. CFC
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III. Ozone depletion
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B. CO2
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II. Global Warming
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C. BOD
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IV. Water Pollution
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D. MIC
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I. Bhopal Gas Tragedy
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