Question

Primary constituents of photochemical smog are
A) $S{O_2}$ and \[CO\]
B) \[C{O_2}\] and \[N{O_2}\]
C) \[N{O_2}\] and unsaturated hydrocarbons
D) Hydrocarbons and CFCs.

Answer 1

Hint: Photochemical smog is also known as summer smog. It is a type of smog, which is produced when UV light arising from the sun interacts with the oxides of nitrogen present in the atmosphere. This smog is commonly like a brown haze and seen in highly populated cities and possess warm climates.

Complete answer:
The photochemical form is made by complex sequences of chemical reactions involving sunlight, oxides of nitrogen, and volatile organic compounds, which are present in the atmosphere as a result of air pollution. The generation of photochemical smog is nearly related to the concentration of primary pollutants in the atmosphere.
Some examples of primary pollutants of photochemical smog include oxides of nitrogen such as nitric oxide, nitrogen dioxide, and nitrous oxide, and most VOCs (volatile organic compounds). Some examples of secondary pollutants that contribute to the formation of photochemical smog comprise aldehydes, tropospheric ozone, and peroxyacyl nitrates (often abbreviated to PAN). It has a number of negative effects on the environment and human beings. It can cause eye irritation.

The correct option is ‘C’ - \[{\mathbf{N}}{{\mathbf{O}}_2}\] and unsaturated hydrocarbons.

Additional information: Photochemical smog is made by a complex and long series of chemical reactions including sunlight, oxides of nitrogen, and volatile organic compounds that are present in the atmosphere, this results in air pollution. These reactions sometimes result in the formation of ground-level ozone and certain airborne particles. The formation of this kind of smog is very much related to the concentration of primary pollutants in the atmosphere. It is also affected by the concentration of secondary pollutants.

Note:
Some important points to remember:
Photochemical smog is most prominently visible during the mornings and afternoons.
 \[N{O_2}\] and unsaturated hydrocarbons are the primary constituents of photochemical smog.
These primary constituents are introduced into the atmosphere via vehicular emissions and industrial processes.