Chlorofluorocarbons CFCs are synthetic compounds containing carbon, chlorine, and fluorine atoms. They were widely used as refrigerants, aerosol propellants, and solvents in the past. However, it was discovered that CFCs contribute significantly to the depletion of the ozone layer in the Earth's stratosphere.The ozone layer is crucial for life on Earth as it absorbs harmful ultraviolet UV radiation from the sun, particularly UV-B and UV-C, which can cause skin cancer, cataracts, and damage to the immune system in humans, as well as harm to other organisms.The process of ozone depletion by CFCs involves several chemical reactions. Here's a simplified overview of the process:1. Release and transport of CFCs: CFCs are released into the atmosphere from various human activities. Over time, they are transported to the stratosphere by atmospheric circulation.2. Photodissociation of CFCs: In the stratosphere, CFCs are exposed to UV radiation, which causes them to break down photodissociation and release chlorine atoms. For example, the photodissociation of CFC-12 CCl2F2 can be represented as: CCl2F2 + UV light Cl + CClF23. Chlorine reacts with ozone: The released chlorine atoms are highly reactive and can react with ozone O3 molecules, leading to the formation of chlorine monoxide ClO and molecular oxygen O2 : Cl + O3 ClO + O24. Regeneration of chlorine atoms: The chlorine monoxide ClO can then react with another ozone molecule, forming molecular oxygen O2 and regenerating the chlorine atom: ClO + O3 Cl + 2O2The regenerated chlorine atom can then react with more ozone molecules, repeating steps 3 and 4. This creates a catalytic cycle in which a single chlorine atom can destroy thousands of ozone molecules before it is eventually removed from the stratosphere by other chemical reactions.The net effect of steps 3 and 4 is the conversion of two ozone molecules into three molecular oxygen molecules: 2O3 3O2This process leads to the depletion of the ozone layer, allowing more harmful UV radiation to reach the Earth's surface. In response to this discovery, the production and use of CFCs have been phased out under the Montreal Protocol, an international treaty designed to protect the ozone layer.