What is ozone? Explain the formation of ozone?What is the effect of ozone depletion?
Class 10 CBSE
Answers
Ozone Layer and its formation:
The ozone layer is a thin layer in the atmosphere at an altitude of about 20-30 km that has a high concentration of ozone gas. It is made up of three atoms of oxygen and is represented as O3. Ozone (O3) is formed by the absorption of Ultra-Violet (UV) light by oxygen (O2) molecules. These molecules react with each other and form ozone (O3). In this process, they absorb the UV rays from the sun and prevent it from reaching the earth’s surface. This layer acts as UV filter – the earth’s natural sunscreen!
UV rays are very harmful to living things. It can cause diseases like skin cancer and can also alter the climate drastically. The ozone layer protects us from these harmful rays and is essential for life on earth.
The ozone layer is not uniform throughout the earth; it is found in a thick layer at some places and a thin layer at others. If this layer becomes too thin, it cannot stop the UV rays from entering the earth and we say that a hole is formed in the ozone layer. Antarctica has the biggest ozone hole followed by the Arctic region and the Tibetan plateau. In these places, the layer was naturally thin, but over the years due to air pollution, these holes have grown bigger and thinner. They are a serious cause of worry across the world.
Causes of Ozone Layer Depletion
The primary reason behind the reduction of the ozone layer is the use of Hydro- Chloro-fluoro-carbons (HCFCs) and chloro-fluoro-carbons ( CFCs). They are compounds of chlorine, fluorine, and carbon such as CF3Cl, CHCl2F etc. These are used as refrigerants in refrigerators, air conditioners, and in cooling plants. These molecules can destroy O3 molecules and therefore depletion of the O3 layer.
Nitrogen oxides such as nitrous oxide are also very reactive to O3 and are also responsible for holes in the ozone layer. These molecules are released by burning fossil fuels by cars and especially airplanes which fly near the ozone layer.
Since 1975, the hole has increased in size due to depletion in the ozone layer. Reductions of up to 70% have been found in some areas
Answer:
Ozone layer is the outermost layer of the earth's atmosphere which is composed of ozone gas which protects the earth from UV rays.
It is created when Ultraviolet radiation strikes the stratosphere splitting oxygen molecules to atomic oxygen.
The atomic oxygen further combines with oxygen molecules to form ozone.
When chlorine and bromine atom come in contact with the stratosphere, they destroy ozone molecules.
These chorine and bromine atoms are released by cfc's.