Question Discussion & Solution

EXE

The filename extension used in windows-based applications denoting an executable file for Microsoft Windows (.exe).

PDF

Portable Document Format (PDF) developed by Adobe and it is also known as the filename extension of PDF (.pdf) files.

DOC

The filename extension for Word document (.doc) most commonly used in MS-Word.

ZIP

Archive File Format is used to compress one or more files. It is also known as the filename extension of ZIP (.zip).

Element

Description

CFC

• 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.

CO₂

• 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.

BOD

• 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.

MIC

• 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. 

A. CFC

III. Ozone depletion

B. CO2

II. Global Warming

C. BOD

IV. Water Pollution

D. MIC

I. Bhopal Gas Tragedy