Given below are 4 reactions. Two of these reactions will give product which is an equimolar mixture of the d and 1 forms. Identify these 2 reactions. [A] 2- Methylpropene + HI --------- [B] But-1-ene + HBr ----------- [C] 3-Methylbut-1-ene + HI ----------- [D] 3- Phenylpropene + HBr (Peroxide) -----------

Step-by-step solution

For a racemic (equimolar d and l) mixture, the product must have a chiral center formed from an achiral reactant via a planar intermediate (carbocation). [A] 2-Methylpropene + HI Markovnikov addition gives tertiary carbocation 2-iodo-2-methylpropane CH₃ - C(I)(CH₃)₂ . Central carbon has three identical methyl groups achiral. No racemic mixture. [B] But-1-ene + HBr Markovnikov addition gives secondary carbocation 2-bromobutane CH₃ - CHBr - CH₂CH₃ . C-2 is bonded to H, Br, CH₃ , and C₂H₅ chiral center. Attack from ei