Which reaction in each of the following pairs would you expect to be faster?

(b) Thedisplacement byon bromoethane or on bromocyclohexane

It is a nucleophilic substitution reaction in which an old bond is broken, and a new bond is formed. Bothprocessesco-occur. Hence, it’s a single-step reaction.

The two reacting species are involved in the rate-determining steps.

Nucleophiles are the negatively charged ions or the neutral species having the lone pair of electrons ready for bonding.

If the species is a better leaving group, it reacts faster with the nucleophile.

Here, both the substrates are different. Bromoethane is a primary alkane,bromocyclohexane is a secondary alkane and$S_{N}2$reaction is shown by primary alkane showing a single-step reaction.

Bromoethane is a better leaving group thanbromocyclohexane

Bromoethaneshows fast reaction thanbromocyclohexane