Final answer:
Chlorofluorocarbons (CFCs) have the highest O-Zone depletion potential among the options given. They release chlorine atoms in the stratosphere that can destroy ozone molecules for up to two years. The Montreal Protocol aims to phase out CFCs to protect the ozone layer. Option A is correct.
Step-by-step explanation:
Of the substances listed, Chlorofluorocarbons (CFCs) have the highest O-Zone depletion potential. CFCs are compounds made up of chlorine, fluorine, and carbon.
Their stability allows them to persist in the atmosphere long enough to reach the stratosphere, where they are broken down by ultraviolet radiation, releasing chlorine atoms.
These chlorine atoms are highly effective in destroying ozone molecules due to their ability to act as a catalyst; a single chlorine atom can destroy ozone molecules over a period of up to two years, significantly depleting the protective ozone layer.
The Montreal Protocol was established to phase out the production of CFCs and reduce ozone depletion. Despite its success, there are still global challenges in completely eliminating CFC emissions.
Alternatives such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are being used as they have lower ozone depletion potentials; HCFCs, while still containing chlorine, are less stable and decompose more rapidly in the lower atmosphere, preventing as much chlorine from reaching the stratosphere.
HFCs, on the other hand, do not contain chlorine and hence do not affect the ozone layer as CFCs do.