Final answer:
Chlorine-based refrigerants without hydrogen, or CFCs, do not break down in the lower atmosphere for a very long time. They contribute to ozone depletion long after their release, underlining the importance of the Montreal Protocol, which has helped phase out CFCs. The correct duration of their stability is until 40 to 70 years after their release, matching answer option (C).
Step-by-step explanation:
The question concerns the stability of chlorine-based refrigerants without hydrogen in the atmosphere. Specifically, these are chlorofluorocarbons (CFCs) which were commonly used in various applications such as refrigerants, air conditioning systems, foams, and aerosols. CFCs are very stable and do not break down in the lower atmosphere for many years. They eventually diffuse into the stratosphere where they get broken down by ultraviolet (UV) radiation, releasing chlorine atoms which then break down ozone (O3) molecules.
Due to their prolonged stability, CFCs contribute to ozone depletion for a significant period even after being released into the atmosphere. International cooperation led to the Montreal Protocol which aimed to phase out the production and use of CFCs due to their harmful effects on the ozone layer. With CFCs being phased out, substances like hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are being used as alternatives, which are less harmful to the ozone layer.
It is expected that the ozone layer will recover to its normal state by around 2065 due to the major reductions in the release of CFCs and related compounds into the atmosphere. However, any chlorine-based refrigerants without hydrogen can remain so stable that they do not break down in the lower atmosphere until 40 to 70 years after their release, which aligns with answer option (C).