The Montreal Protocol categorizes which substances into two classes based on their ozone-depleting potential?

The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production and consumption of substances known to deplete it. The substances specifically categorized under this protocol include chlorofluorocarbons (CFCs) and halons, which are known for their significant ozone-depleting potential.

CFCs are primarily used in refrigeration, air conditioning, foam production, and aerosol propellants. Halons, on the other hand, have mainly been used in fire extinguishers. Both of these classes of compounds release chlorine and bromine when they are broken down in the stratosphere, which can lead to the destruction of ozone molecules.

The importance of these substances being classified in this manner lies in the capacity to implement regulatory measures that effectively reduce their presence in the atmosphere. The Montreal Protocol has been successful in phasing out many of these harmful substances, leading to the gradual recovery of the ozone layer.

The other options presented do not directly involve substances that are classified under the Montreal Protocol for ozone depletion. Carbon dioxide (CO2) and peroxyacetyl nitrate (PAN), for instance, while important from a greenhouse gas perspective, are not considered ozone-depleting substances. Similarly, sulfur dioxide (SO