The reaction O₂ → 2O, which occurs in the stratosphere, does not occur in the troposphere to produce ozone due to

Correct option is B

Introduction
· The formation of ozone (O_3) in the Earth's atmosphere begins with the photolysis (splitting) of molecular oxygen (O_2).
· This process is part of the Chapman Cycle, a series of photochemical reactions that maintain the ozone layer in the stratosphere.
· For a chemical bond to break, the incoming solar radiation must possess enough energy to overcome the bond dissociation energy of the oxygen molecule.

Information Booster
· The correct answer is absence of $$\lambda < 242\text{ nm}$$​ radiation, as these high-energy Ultraviolet-C (UVC) rays are required to break the strong double bond in an O_2 molecule.
· Oxygen molecules (O_2) absorb solar radiation in the UVC range (wavelengths shorter than 242nm). This absorption is so efficient that almost all such radiation is "filtered out" by the time sunlight reaches the lower atmosphere.
· In the stratosphere, these rays are abundant, allowing O_2 to split into two highly reactive oxygen atoms (O + O). These atoms then collide with other O_2 molecules to form ozone (O_3).
· In the troposphere, the sunlight lacks these specific short wavelengths. Consequently, the direct dissociation of O_2 cannot occur at ground level.
· This is why "bad ozone" at the surface is not formed from oxygen directly, but rather from the photolysis of Nitrogen Dioxide (NO_2) at much longer wavelengths$$\lambda < 424\text{ nm}$$​

Additional Knowledge
· Lower tropospheric temperature is incorrect because the photolysis of oxygen is a photochemical process driven by light energy (photons), not by the ambient kinetic energy (heat) of the air.
· High air pressure and high gas concentrations actually favor the second step of ozone formation (where O and O_2 must collide), but they cannot trigger the first step if the necessary high-energy photons are missing.
· The "Ozone Shield" is a direct result of this phenomenon: the atmosphere's upper layers sacrifice O_2 and O_3 to absorb the most dangerous UV radiation, protecting the troposphere from germicidal 242  nm rays.
· The bond energy of O_2 is approximately $$498\text{ kJ/mol}$$, which corresponds exactly to the energy carried by a photon with a wavelength of roughly $$240-242\text{ nm}$$​