The action of UV light on oxygen produces which toxic gas?

The action of ultraviolet (UV) light on oxygen leads to the formation of ozone. When UV radiation interacts with oxygen molecules (O₂) in the atmosphere, it causes them to dissociate into individual oxygen atoms. These free oxygen atoms can then react with other O₂ molecules to form ozone (O₃). This reaction is significant in the stratosphere, where the ozone layer plays a crucial role in protecting the Earth from harmful UV radiation. Ozone is a form of oxygen that has distinct properties and is known for its strong oxidizing capabilities, which can be harmful at ground level, contributing to air pollution.

The other gases listed do not form as a direct result of the UV light interaction with oxygen. Carbon monoxide is primarily produced from incomplete combustion of fossil fuels, nitrogen dioxide is a byproduct of combustion processes at high temperatures, and sulfur dioxide is released from volcanic eruptions and industrial processes involving sulfur-containing materials. Therefore, the correct answer identifies ozone as the gas produced when UV light interacts with oxygen.