- AR-134a
- BR-410A
- CR-22
- R-11
Correct answer
R-11
Why
R-11 (CFC-11) has an ODP of 1.0, which is the baseline. R-22 has 0.055, while R-134a and R-410A have ODPs of 0.
The concept behind this question
Ozone depletion potential (ODP) measures how much damage a compound does to stratospheric ozone, and chlorine is the culprit. CFCs carry the most chlorine and the highest ODP, HCFCs carry less and are transitional, and HFCs contain no chlorine and have an ODP of zero. Zero ODP is not the same as harmless — many HFCs have high global warming potential (GWP), which is what the more recent phase-down addresses.
More questions on this topic
- Where is the ozone layer located?
- What does the ozone layer protect us from?
- Which element in refrigerants is primarily responsible for ozone depletion?
- What type of refrigerant is R-22?
- What happens to CFCs and HCFCs when they reach the stratosphere?
- How many ozone molecules can one chlorine atom destroy?
Exam-style practice question. Not an official EPA exam question.