The correct answer is option 3: Nitrogen oxides.
Nitrogen oxides are a key ingredient in the formation of photochemical smog. Photochemical smog is a type of smog that is formed when sunlight reacts with pollutants in the atmosphere. Nitrogen oxides, also known as NOx, are produced from the combustion of fossil fuels, such as in car engines and power plants.
When nitrogen oxides are released into the atmosphere, they undergo a series of chemical reactions facilitated by sunlight. These reactions result in the formation of photochemical smog, which consists of harmful pollutants like ozone, aldehydes, and other secondary pollutants. Nitrogen oxides are particularly important in the formation of photochemical smog because they are highly reactive and can react with other pollutants to form secondary pollutants that are harmful to human health and the environment.
The other options, carbon oxides, halogenated hydrocarbons, and lead particles, are not key ingredients in the formation of photochemical smog. Carbon oxides, such as carbon monoxide and carbon dioxide, can contribute to air pollution but are not directly related to the formation of photochemical smog. Halogenated hydrocarbons are compounds containing halogens, and while they can contribute to