Which of the following substances undergoes photolytic decomposition to deplete ozone?

Methyl bromide is known for its role in ozone layer depletion, primarily due to its ability to undergo photolytic decomposition when exposed to ultraviolet (UV) radiation in the atmosphere. The photolysis of methyl bromide releases bromine atoms, which are highly effective in catalyzing the breakdown of ozone (O3) into oxygen (O2). One bromine atom can destroy thousands of ozone molecules before being deactivated.

In contrast, substances like carbon dioxide, nitrous oxide, and ammonia do not have the same photolytic properties or do not release ozone-depleting halogens upon photolysis. Carbon dioxide is a significant greenhouse gas but does not contribute to ozone depletion. Nitrous oxide, while a potent greenhouse gas, mainly contributes to warming and doesn't directly deplete the ozone layer in the same manner as methyl bromide. Ammonia, being a nitrogen compound, does not produce ozone-depleting substances through photolytic reactions.

Thus, methyl bromide stands out due to its unique reactivity and the direct impact it has on the ozone layer, making it the substance that undergoes photolytic decomposition specifically depleting ozone.