Final answer:
Supermarkets are moving away from chlorofluorocarbons (CFCs) due to their ozone-depleting effects and are switching to hydrofluorocarbons (HFCs), which are more ozone friendly and do not contribute to ozone depletion.
Step-by-step explanation:
When considering a fire in a supermarket, most supermarkets have abandoned the use of chlorofluorocarbons (CFCs) and are switching to hydrofluorocarbons (HFCs) which are more ozone friendly. The correct answer is option 2: Hydrofluorocarbons (HFCs).
Chlorofluorocarbons (CFCs) are harmful to the ozone because when they are broken down by ultraviolet radiation in the stratosphere, they release chlorine atoms which can destroy ozone molecules, thus contributing to ozone depletion. To mitigate this environmental concern, substances that are less damaging were sought. Hydrofluorocarbons (HFCs), such as CH₂FCF₃, do not contain chlorine or bromine, thus they do not form radicals that destroy ozone, making them more favorable alternatives for use in various applications including fire suppressants, refrigerants, and propellants.
Hydrochlorofluorocarbons (HCFCs) are also an alternative, as these chemicals break down more readily in the troposphere, meaning fewer reach the stratosphere to cause ozone depletion. However, HFCs are the more ozone-friendly choice and are increasingly used to replace CFCs.