Which of the following refrigerants is known to have a high ODP?

The choice of R-12 as having a high Ozone Depletion Potential (ODP) is accurate because R-12, a chlorofluorocarbon (CFC), contains chlorine atoms that can deplete the ozone layer when released into the atmosphere. CFCs like R-12 break down in the stratosphere, releasing chlorine, which catalyzes the breakdown of ozone (O3) into oxygen (O2). This reaction is detrimental to the ozone layer, hence R-12 is considered to have a high ODP.

In contrast, refrigerants like R-134A, R-410A, and R-22 are designed with lower ODP values. R-134A is a hydrofluorocarbon (HFC) and contains no chlorine, resulting in a negligible impact on the ozone layer. R-410A, which is also an HFC, similarly has no ozone-depleting chemicals. Although R-22 does contain some ozone-depleting potential due to its chlorine component, its ODP is still significantly lower than that of R-12. This distinction highlights the ongoing shift in refrigerant usage towards those that are ozone-friendly, in line with global environmental agreements such as the Montreal Protocol