Previous Year Question
With reference to ‘ozone layer’, which of the following statements is/are correct?
Ozone layer shields the surface of the earth from the ultra-violet radiations from the sun.
Ozone depletion has been linked to the chlorofluorocarbons.
Select the correct answer from the code given below:
Only 2
Neither 1 nor 2
Both 1 and 2
Only 1
Correct Answer: C
Detailed Solution
The ozone layer is located mainly in the stratosphere and absorbs a large proportion of harmful ultraviolet radiation from the Sun, particularly UV-B and nearly all UV-C radiation. In this way, it protects humans, animals, plants and other forms of life on Earth from excessive ultraviolet radiation. Therefore, Statement 1 is correct.
Statement 2 is also correct. Chlorofluorocarbons or CFCs are very stable in the lower atmosphere and can gradually reach the stratosphere. There, intense ultraviolet radiation breaks them down and releases chlorine atoms. These chlorine atoms destroy ozone molecules through catalytic reactions and can become available again to participate in the destruction of many additional ozone molecules.
The best-known example of ozone depletion is the ozone hole that develops over Antarctica. Because of the effects of CFCs and other chlorine- and bromine-containing compounds, the 1987 Montreal Protocol was adopted to control the production and consumption of ozone-depleting substances. Global action has greatly reduced the use of many major ozone-depleting substances and has contributed to progress towards recovery of the ozone layer.