Which compounds are less stable than CF's and break down before reaching the stratosphere?

The correct answer highlights that HCFCs (Hydrochlorofluorocarbons) and HFCs (Hydrofluorocarbons) are less stable than CFCs (Chlorofluorocarbons) and tend to break down in the lower atmosphere, before they can reach the stratosphere.

HCFCs and HFCs have a shorter atmospheric lifetime compared to CFCs, which means they do not persist in the atmosphere long enough to significantly contribute to ozone depletion. The structure of HCFCs and HFCs includes hydrogen atoms, which make them more reactive and prone to breakdown through atmospheric processes such as photolysis. This reaction occurs when ultraviolet light breaks down these compounds, leading to their degradation into less harmful substances before they can reach the stratosphere, where ozone depletion primarily occurs.

In contrast, CFCs are more stable and resistant to photochemical breakdown, allowing them to reach the stratosphere where they can release chlorine atoms that significantly contribute to ozone depletion. This stability is one of the reasons CFCs were phased out in many applications due to their adverse environmental impact.

Understanding the stability of these compounds in the atmosphere is crucial for assessing their environmental effects, particularly concerning