Nucleophilic Substitution | MCQs

Explanation

 Leaving group ability:

A good leaving group is a species that can easily depart from a molecule taking a pair of electrons with it. 

Halide trend:

Among halogens (I, Br, Cl, F), iodide (I-) is the best-leaving group because it is the weakest base, meaning it is most stable with a negative charge. 

Explanation

In the SN2 mechanism, the C-X bond breaks and the C-Nu bond forms simultaneously in a single concerted step.

It involving a backside attack by the nucleophile and inversion of configuration at the carbon center.