Final answer:
The statement is true; CFCs are stable carriers of chlorine and contribute to ozone depletion by releasing chlorine when exposed to UV radiation in the stratosphere, leading to a global effort to phase them out.
Step-by-step explanation:
The statement that CFC refrigerants are stable and act as 'carriers' that store chlorine until they reach the upper atmosphere, where they then release the ozone-depleting chlorine, is true. Chlorofluorocarbons (CFCs) are composed of chlorine, fluorine, and carbon atoms. Due to their extreme stability, CFCs can slowly ascend into the stratosphere without decomposing in the lower atmosphere. When exposed to ultraviolet (UV) radiation in the stratosphere, CFCs break down, releasing chlorine atoms which then catalyze the destruction of ozone molecules. This process can continue for a single chlorine atom for up to two years, leading to substantial ozone depletion. As a result, there has been a global effort to phase out the use of CFCs, and they are being replaced with more environmentally friendly substances like hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs).