Delhi Police Constable Exam Model Paper 3

Ozone gas is continuously formed by the action of UV rays on molecular oxygen and also degraded into molecular oxygen in the stratosphere.

• There should be abalance between production and degradation of ozonein the stratosphere.
• Of late, the balance has been disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs).
• CFCs find wide use as refrigerants . CFCs discharged in the lower part of the atmosphere move upward and reach the stratosphere.
• In the stratosphere, UV rays act on them releasing Cl atoms.
• Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction.
• Hence, whatever CFCs are added to the stratosphere, they have permanent and continuing effects on Ozone.
• ODS include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons , methyl bromide, carbon tetrachloride, hydro Bromo fluorocarbons,chlorobromomethane , and methyl chloroform.
• ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere.