Chlorination of alkane is a photochemical process. It is initiated...

Chlorination of alkanes is a free radical substitution reaction.

The initiation step involves the breaking of the $Cl-Cl$ bond in the presence of ultraviolet light (h\nu$) or heat.<br><br>The bond breaks symmetrically such that each chlorine atom retains one electron, forming two chlorine free radicals.<br><br>$Cl_2 \xrightarrow{h\nu}$2Cl^{\bullet}$

This symmetrical breaking of a covalent bond is known as homolysis or homolytic cleavage.

Answer: homolysis