Which one of the following alkenes forms the same product with HBr in the absence as well as in the presence of peroxide?

Step-by-step solution

Symmetrical alkenes yield the same product with HBr in the presence and absence of peroxide because both carbons of the double bond are equivalent. 2-butene ( CH₃-CH=CH-CH₃ ) is a symmetrical alkene. Addition of HBr to 2-butene in the absence of peroxide (electrophilic addition) yields 2-bromobutane. Addition of HBr to 2-butene in the presence of peroxide (free radical addition) also yields 2-bromobutane. 1-butene, propene, and 2-methylpropene are unsymmetrical alkenes and will yield different products (Markovnikov