Plz explain this sir ........ in most of the cases there is always the

in most of the cases there is always the inverted product in excess over the other isomer, so it is believed that carbocation and leaving group exist for a while as an intimate ion pair and the attack of nucleophile during this time takes place only on the back side of carbOcation, but not on the front side giving rise to inversion. Now attack of nucleophile on free symmetrical carbocation occurs from the backside or from the side with equal probability. S+ S R IX Solvent separated ion pair R-X RX R intimate ion pair SH SH R S-R+R-S S (inversion) S-R+R-S z% (100-z)% 50% 50% (mixture) racemic)