The S N 2 reaction involves back-side attack and therefore results in a "Walden Inversion." For which one of the substrates shown would you be able to demonstrate that such back-side attack with "Walden Inversion" has in fact occurred?

Step-by-step solution

For SN 2 reaction: 1. It is single step reaction. 2. In this reaction nucleophile attacks from the back side of the leaving group. If chiral carbon is present then it will change its configuration. So, to observe inversion, the substitution must occur at a chiral centre.