JAMB Biology 2018 Paper

Concept:Ozone layer depletion is mainly caused by human-made chemicals, especially chlorofluorocarbons, which destroy ozone molecules.Explanation:The ozone layer in the upper atmosphere absorbs harmful ultraviolet radiation from the Sun.Chlorofluorocarbons ($\mathrm{CFCs}$) and other halogenated ozone-depleting substances release chlorine atoms when they break down in the stratosphere.These chlorine atoms react with ozone ($\mathrm{O_3}$) molecules and convert them into ordinary oxygen ($\mathrm{O_2}$), reducing the protective ozone layer.This process lowers the atmosphere's ability to block dangerous UV rays.Oxygen ($\mathrm{O_2}$) is natural and does not damage ozone.Nitrogen oxide can participate in some reactions, but its effect is minor compared to $\mathrm{CFCs}$.Sulphur dioxide mainly causes acid rain, not ozone layer damage.Thus, the most significant cause of ozone layer damage is chlorofluorocarbons.Answer:C. Chlorofluorocarbons