Final answer:
2-bromohexane (option b) would undergo E₂ dehydrohalogenation to give 1-hexene as a pure alkene.
Step-by-step explanation:
The organic bromide that would undergo E₂ dehydrohalogenation to give 1-hexene as a pure alkene is 2-bromohexane (option b).
When 2-bromohexane undergoes E₂ dehydrohalogenation, it eliminates HBr to form a double bond between the second and third carbon atoms, resulting in the formation of 1-hexene as a pure alkene.