When solving a problem that asks you to predict a reaction product, begin by looking at the functional group(s) in the reactants and deciding what kind of reaction is likely to occur : In the present instance, the reactant is an alkene that will probably undergo an electrophilic addition reaction with HCl. Next recall what you know about electrophilic addition reactions, addition reactions follow Markovnikov’s rule, so the –Cl will add to the more highly substituted carbon.