🔍 Key Concepts

• Ozone depletion potential (ODP) is highest for older CFCs (chlorofluorocarbons), lower for HCFCs (hydrochlorofluorocarbons), and very low/negligible for HFCs (hydrofluorocarbons). • Know which common marine refrigerants are CFCs, HCFCs, and HFCs. • International environmental regulations (like the Montreal Protocol) targeted phase-out of the worst ozone-depleting refrigerants first.

💭 Think About

• Which of these refrigerants was phased out earliest because of its impact on the ozone layer? • Among CFCs, HCFCs, and HFCs, which chemical family is known to have the greatest ozone depletion potential? Then, which option belongs to that family? • Look at the chemical family for each choice: which one has no chlorine, which has one hydrogen, and which has no hydrogen—how does that relate to ODP?

✅ Before You Answer

• Identify which choice is a CFC (typically the worst for ozone). • Confirm which option(s) are HCFCs (transitional, lower ODP but not zero) and which are HFCs (negligible ODP). • Before selecting, ask: which of these was most aggressively regulated and banned earliest for ozone protection? That one will have the highest ODP.