Which of the following refrigerants is most stable in the lower atmospheres of Earth?

The most stable refrigerants in the lower atmospheres of Earth are typically those that exhibit low reactivity and a longer atmospheric lifetime. Chlorofluorocarbons (CFCs) are known for their stability in the lower atmosphere due to their chemical structure, which resists breakdown by sunlight and other atmospheric processes. This stability allows them to persist for long periods, leading to concerns about their contribution to ozone depletion when they eventually reach the stratosphere.

CFCs are fully halogenated compounds, meaning they contain carbon, chlorine, and fluorine atoms. Their molecular stability results in a low tendency to react with other atmospheric constituents in the lower atmosphere. However, it's important to note that, while CFCs are stable, their long atmospheric lifetimes can have negative environmental impacts once they reach higher altitudes.

Other refrigerants, such as HFCs (hydrofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFOs (hydrofluoroolefins), have been developed to reduce environmental impact, particularly regarding ozone depletion and global warming potential. However, they tend to be less stable in the lower atmosphere compared to CFCs due to various reasons, including