Question

Assertion : UV radiation causes photodissociation of ozone into $O_2$ and O. Thus causing damage to the stratospheric ozone layer.

Reason : 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

The correct option is D If both assertion and reason are false.

UV radiation causes the photodissociation of the CFCs, HFCs, methyl bromine etc. to release the reactive chlorine and bromine radicals. These reactive species then react with the ozone to release $O_2$ and O. The break down of ozone molecules, reduces ozone's ultraviolet radiation-absorbing capacity. Thus, the destruction of this stratospheric ozone layer is caused by the chemicals containing chlorine and bromine.

The ozone layer and the global warming are not the same thing and neither is the cause of the other. Global warming is caused by the greenhouse gases. However, the CFCs that destroys ozone are also a potent greenhouse gases. They are present in small traces in the atmosphere but are considered as one of the contributor of greenhouse effect.

Therefore, both assertion and reason are false.