The reactivity in SN2
reactions follows the reverse order as the steric hinderance around the
electrophilic carbon increases in that order (ii) C6H5C(CH3)(C6H5)Br > C6H5CH(C6H5)Br >  C6H5CH(CH3)Br > C6H5CH2Br (SN1)
C6H5C(CH3)(C6H5)Br < C6H5CH(C6H5)Br <  C6H5CH(CH3)Br < C6H5CH2Br (SN2)
Of the two secondary bromides, the carbocation intermediate obtained
from C6H5CH(C6H5)Br is more stable than obtained from C6H5CH(CH3)Br
because it is stabilised by two phenyl groups due to resonance Therefore,
the former bromide is more reactive than the latter in SN1 reactions A
phenyl group is bulkier than a methyl group