The gas 'A' is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in stratosphere. The intermediates formed initially from the gas 'A' are:

The gas described in the question is unreactive in the lower atmosphere (troposphere), non-toxic and non-flammable, and is able to reach the stratosphere where it undergoes photochemical dissociation by ultraviolet radiation.

These are the characteristic properties of chlorofluorocarbons (CFCs), commonly known as Freons. The most common example discussed in standard textbooks is Freon-12, $$\mathrm{CF_2Cl_2}$$. Because CFCs are chemically inert in the lower atmosphere, they survive long enough to drift into the stratosphere.

Once CFCs reach the stratosphere, they are exposed to high-energy ultraviolet (UV) radiation. This radiation provides sufficient energy to cause homolytic cleavage of their chemical bonds.

Since the carbon-chlorine bond is weaker than the carbon-fluorine bond, the $$\mathrm{C-Cl}$$ bond breaks preferentially.

The photochemical reaction is

$$\mathrm{CF_2Cl_2(g)\xrightarrow{UV}Cl^\bullet(g)+CF_2Cl^\bullet(g)}$$

Here,

• $$\mathrm{Cl^\bullet}$$ is the chlorine free radical.
• $$\mathrm{CF_2Cl^\bullet}$$ is the chlorodifluoromethyl free radical.

The chlorine free radical subsequently reacts with ozone ($$\mathrm{O_3}$$), initiating a chain reaction that leads to ozone depletion.

Therefore, the initial intermediates formed by the UV dissociation of gas A ($$\mathrm{CF_2Cl_2}$$) are $$\mathrm{Cl^\bullet}$$ and $$\mathrm{CF_2Cl^\bullet}$$.

Hence, the correct answer is $$\boxed{\text{Option (B)}}$$.