Consider the following reactions that produce alkyl halides as their major products: (I) Addition of HBr to 2-methylbut-2-ene (II) Addition of HBr to but-1-ene (III) Addition of HBr to ethene The correct increasing order of the rate of dehydrohalogenation of these resulting major alkyl halides with alcoholic KOH is:

Step-by-step solution

According to Markovnikov's rule, the addition of HBr to the given alkenes yields the following major alkyl halides: (I) 2-Methylbut-2-ene + HBr 2-Bromo-2-methylbutane (a 3^ alkyl halide) (II) But-1-ene + HBr 2-Bromobutane (a 2^ alkyl halide) (III) Ethene + HBr Bromoethane (a 1^ alkyl halide) The rate of dehydrohalogenation (E2 reaction) with alcoholic KOH depends on the stability of the transition state and the resulting alkene. Tertiary ( 3^ ) alkyl halides form more highly substituted, stable alkenes and react th