Question

Which of the following is a photochemical reaction product?
(A) Fluorides
(B) CO and ${ CO }_{ 2 }$
(C) ${ SO }_{ 3 }$
(D) ${ O }_{ 3 }$

Answer 1

Photochemical reaction product is a compound produced by the reaction of another molecule or atom with Sun's radiation. The process is triggered due to light energy being absorbed by a substance’s molecules.

Complete answer:
The Ozone (${ O }_{ 3 }$) molecule is a photochemical reaction product which forms due to the action of the UV rays with the oxygen molecules. When the ultraviolet rays of the sun enter the Earth's atmosphere it reacts with the oxygen molecules to form atoms of oxygen which further reacts with the molecules to form the three oxygen complexes named ozone.

Additional Information: Fluorides are the simplest fluorine anion which is mainly found in water and plants. All the fluorine found on the Earth's surface is in the form of fluorides.
Carbon monoxide is a colorless, odorless, and tasteless flammable toxic gas that consists of one carbon atom and one oxygen atom. These are produced by partial oxidation of carbon-containing compounds. The largest source of this gas is the Troposphere due to photochemical reactions.
Carbon dioxide, on the other hand, is a colorless gas, vital for the process of photosynthesis. The current concentration in the atmosphere is $0.04\%$ and its main natural sources are volcanoes, hot springs, and geysers.
Sulfur trioxide is a significant pollutant and is one of the primary causes of acid rain. In the atmosphere, it is produced by direct but slow oxidation of sulfur dioxide. Its main source is industrial reactions where it is produced in a large quantity which contributes to air pollution.
So, the correct answer is "${ O }_{ 3 }$".

Note: The photochemical reaction is triggered when light energy gets absorbed by a molecule or atoms and leads the molecule to experience an excited state which alters its physical and chemical properties. Here the photochemical reaction product ozone is an inorganic molecule and is pale blue in color. It is present in very low concentration but is present abundantly in the stratosphere where it forms a layer called the ozone layer. The ozone layer has a significant role in the absorption of the Sun's ultraviolet radiation.