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:

A

$$\dot{C}H_3 + \dot{C}F_2Cl$$

B

$$\dot{C}l + \dot{C}F_2Cl$$

C

$$Cl\dot{O} + \dot{C}H_3$$

D

$$Cl\dot{O} + \dot{C}F_2Cl$$