Question

Data shows that chlorine in the stratosphere comes mainly from CFCs rather than from natural sources such as volcanoes because:

1) CFCs are more abundant in the stratosphere than natural sources
2) CFCs have a longer atmospheric lifetime than natural sources
3) CFCs have a higher chlorine content than natural sources
4) CFCs are more reactive with ozone than natural sources

Answer 1

Chlorine in the stratosphere mainly comes from CFCs due to their long atmospheric lifetime, releasing chlorine atoms when decomposed by ultraviolet light, which then destroy ozone molecules.

Step-by-step explanation:

Data shows that chlorine in the stratosphere comes mainly from CFCs (chlorofluorocarbons) rather than from natural sources such as volcanoes for several reasons. The most evident reason is due to the long atmospheric lifetime of CFCs, which means they remain in the atmosphere longer, enabling them to reach the stratosphere where they can do damage to the ozone layer. Once CFCs reach the stratosphere, ultraviolet light causes CFCs to decompose, releasing atomic chlorine. The chlorine atoms then react with ozone molecules (O3), resulting in a net removal of ozone from the stratosphere. Because of their stability, CFCs do not break down in the lower atmosphere and can carry chlorine atoms into the stratosphere over time. Each chlorine atom can destroy thousands of ozone molecules because chlorine acts as a catalyst in the process. This is why CFCs, once used as aerosol propellants in spray cans and as refrigerants, have contributed significantly to ozone depletion. Worldwide efforts have reduced the use of CFCs, leading to a slow recovery of the ozone layer.