The major product for this elimination reaction is CH2=CH2 ethene and the mechanism is E2 bimolecular elimination .Here's the step-by-step mechanism for the reaction:1. The KOH potassium hydroxide acts as a strong base in this reaction. The hydroxide ion OH- from KOH abstracts a -hydrogen a hydrogen atom on the carbon adjacent to the carbon attached to the bromine atom from the CH3CH2Br molecule.2. Simultaneously, the electrons from the C-H bond form a double bond between the two carbons C=C , and the C-Br bond breaks, releasing the bromide ion Br- .3. The final products are ethene CH2=CH2 and potassium bromide KBr .The overall reaction can be written as:CH3CH2Br + KOH CH2=CH2 + KBr