Ozone layer above the surface of Earth provides a shield against A. X-rays B. Ultra-violet rays C. Gamma rays D. Infra-red rays

The correct answer is: B. Ultra-violet rays.

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 the 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 contribute to the destruction of the ozone layer. Chlorofluorocarbons (CFCs), which were once widely used in refrigerants and aerosol propellants, are particularly harmful to the ozone layer. CFCs are released into the atmosphere, where they are broken down by ultraviolet radiation. The chlorine atoms that are released then react with ozone, destroying it.

The Montreal Protocol, an international treaty signed in 1987, has helped to reduce the use of CFCs and other ozone-depleting substances. As