The rearrangement reaction that occurs when 2-bromopentane is treated with sodium ethoxide in ethanol is the E2 elimination reaction, which leads to the formation of an alkene. The mechanism of this reaction is as follows:1. Sodium ethoxide NaOEt acts as a strong base in this reaction. The ethoxide ion EtO- abstracts a proton H+ from the -carbon carbon adjacent to the carbon attached to the bromine atom of 2-bromopentane. 2. Simultaneously, the electrons from the C-H bond that was broken form a double bond between the -carbon carbon attached to the bromine atom and the -carbon.3. At the same time, the C-Br bond breaks, and the bromide ion Br- leaves as a leaving group.4. The final product is an alkene. In this case, there are two possible products: 2-pentene the major product and 3-pentene the minor product . The major product is formed according to Zaitsev's rule, which states that the more substituted alkene is the major product in an elimination reaction.Overall, the E2 elimination reaction occurs in a single concerted step, with the base abstracting a proton, the formation of the double bond, and the departure of the leaving group happening simultaneously.