Q.Homolytic fission of covalent bond leads to the formation of

Homolytic cleavage is the symmetrical splitting of a covalent bond in which each of the two previously-bonded atoms keeps exactly one electron of the original bonding pair, denoted by a half-headed (fish-hook) arrow. It requires an energetic trigger -- high temperature or UV light -- and happens most readily in non-polar bonds between atoms of similar electronegativity, where there is no built-in pull favouring either atom.

Homolysis produces free radicals: short-lived, highly reactive species carrying an unpaired electron. Reagents deliberately used to trigger homolytic cleavage are called free-radical initiators -- classic examples are AIBN (azobisisobutyronitrile) and peroxides such as benzoyl peroxide, both widely used to start polymerisation reactions. Photolysis of benzoyl peroxide ($C_6H_5$-CO-O-O-CO-$C_6H_5$) under UV light splits the weak O-O bond homolytically; the resulting benzoyloxy radicals immediately decarboxylate (lose $CO_2$) to give phenyl free radicals, which then initiate polymerisation. …