Question

Assertion (A) UV-radiation causes photodissociation of enzyme into $O _{2}$ and $O$. Thus causing damage to the stratospheric. ozone layer.
Reason (R) Ozone hole is resulting in global warming and climate change.

• A. If both Assertion and Reason are true and Reason is correct explanation of Assertion.
• B. if both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
• C. If Assertion is true but Reason is false.
• D. If both Assertion and Reason are false.

Answer 1

Answer: (C)

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, degrades into molecular oxygen in the stratosphere. There should be a balance between the production and degradation of ozone in the stratosphere. The balance has been disrupted due to the enhancement of ozone degradation by chlorofluorocarbons (CFCs). 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. Cl atoms are not consumed in the reaction. Hence, whatever CFCs are added to the stratosphere, they have permanent and continuing effects on ozone levels. This has resulted in the formation of a large area of the thinned ozone layer, commonly called the ozone hole.
The ozone hole, however, is not the mechanism of global warming. Ultraviolet radiation represents less than one per cent of the energy from the sun not enough to be the cause of the excess heat from human activities. Global warming is caused primarily by putting too much carbon into the atmosphere when coal, gas, and oil are burned to generate electricity or fuels in cars. These gases spread around the planet like a blanket, trapping the solar heat that would otherwise be radiated out into space.