How do you account for the formation of ethane during chlorination of methane?

urgently needed

Actually, the chlorination of methane occurs via free radical mechanism and the ethane is produced as follows:

Free radical Mechanism: The reaction starts with exposure of reactants under light energy and  involves three steps viz, initiation, propagation and termination.

For ex: Let us consider the chlorination of methane under 520-670K temp in light energy,

Step1.: Initiation: At first, the chlorine molecule undergo homolytic fission at 520-670K to give two Chlorine free radicals.

Step2.: Propagation: At this step, the radical attacks on the methane molecule and generates a methyl free radical as

Step.3: Termination: At the end of the reaction, all the free radicals are again attached as

(Ethane)