Consider the conversion, CH33C-Br→alc.KOHA→peroxideHBrB ; The compound ‘B’ in the process is

CH33C-Br→alc.KOHCH32C=CH2→peroxideHBrCH32CH -CH2Br; Step I…Dehydrohalogenation to give isobutene;Step II… Addition of HBr by anti markonikov's rule(free radical addition) without rearrangement to give iso butyl bromide;