The ozone layer is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation. It contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth’s atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 20 to 30 kilometers (12 to 19 mi) above Earth, although its thickness varies seasonally and geographically.
The ozone layer is important because it protects life on Earth from harmful ultraviolet radiation. Ultraviolet radiation can cause skin cancer and other health problems, and it can also damage plants and animals. The ozone layer absorbs most of the Sun’s ultraviolet radiation, preventing it from reaching Earth’s surface.
The ozone layer is constantly being created and destroyed. Ozone is created when oxygen molecules (O2) are split by ultraviolet radiation, and the resulting oxygen atoms (O) combine with other oxygen molecules to form ozone (O3). Ozone is destroyed when it reacts with other chemicals, such as chlorine and bromine.
Human activities have been shown to have a significant impact on the ozone layer. Chlorofluorocarbons (CFCs), which were once widely used in refrigerants and aerosol propellants, are one of the main causes of ozone depletion. CFCs are released into the atmosphere, where they break down and release chlorine atoms. These chlorine atoms react with ozone molecules, destroying them.
The Montreal Protocol, an international treaty signed in 1987, has helped to reduce the use of CFCs and other ozone-depleting substances. As a result, the ozone layer is slowly recovering. However, it is still important to protect the ozone layer by reducing our use of ozone-depleting substances and by taking other steps to reduce our impact on the environment.
The correct answer to the question “Ozone layer is present in” is:
- B. Stratosphere
The stratosphere is the second layer of Earth’s atmosphere, above the troposphere and below the mesosphere. It extends from about 10 to 50 kilometers (6 to 31 mi) above Earth’s surface. The stratosphere is characterized by an increase in temperature with altitude, due to the presence of ozone. Ozone is a gas that absorbs ultraviolet radiation from the Sun, which heats the stratosphere.
The stratosphere is important because it contains the ozone layer, which protects life on Earth from harmful ultraviolet radiation. The stratosphere is also important for aviation, as it is the layer of the atmosphere where commercial airplanes fly.