Question

Ozone hole means
(a)A large-sized hole in the stratosphere layer
(b)Thinning of the ozone layer at the poles
(c)Small holes scattered in the ozone layer
(d)Thickening of the ozone layer at the poles

Answer 1

Hint: The ozone layer is the most important layer present in the stratosphere as it filters the harmful UV rays of the sun and prevents it from entering the earth’s surface. The ozone hole has occurred due to various atmospheric pollutants and CFCs released into the atmosphere. It is the depletion of the ozone layer.

Complete Answer:
The ozone layer is a film of ozone gas that is present in the stratosphere, that envelops the earth and prevents the penetration of harmful UV rays. However, due to global warming and certain ozone-depleting substances such as CFCs, HCFCs, etc that are used as coolants in refrigerators and air conditioners, the ozone layer is being depleted steadily.
This ozone depletion is seen to a much greater extent in the polar regions where there is extreme thinning of the ozone layer leading to phenomena such as the polar ice caps melting. This phenomenon of thinning of the ozone layer in the polar areas is known as the ozone hole.

So, the correct answer is, “Thinning of the ozone layer at the poles”

Note:
-The depletion of the ozone layer around the globe was first noticed around the 1970s and this destruction of ozone can be due to a number of free radicals such as hydroxyl radical, nitric oxide, chlorine radical, etc.
-The major cause for ozone depletion was however attributed to the ozone-depleting substances such as Chlorofluorocarbons(CFCs) and HCFCs, and halons.
-Accordingly many countries adopted the Montreal Protocol in 1987 to slowly phase out the use of these substances and develop substitutes. The measures established were effective in stabilizing the ozone levels to a great extent.