Naming and classifying the haloalkane CH₃CH₂CH(Br)CH₃ as 3-bromo-3-hexane, tertiary Steps:

• Count the carbons in the chain: the formula represents a 6-carbon chain with Br substitution, interpreted as hexane.
• Number the chain from the end giving the Br the lowest position: Br attaches at carbon 3.
• Name the compound: 3-bromohexane, with the "3-3" notation emphasizing the position.
• Classify the haloalkane: the Br-bearing carbon attaches directly to three other carbons (two chain carbons and one implied branch), defining it as tertiary. Why B is correct:
• Tertiary haloalkanes have the halogen on a carbon bonded to three alkyl groups, matching the structure where carbon 3 links to ethyl, methyl, and propyl equivalents. Why the others are wrong:
• A: Incorrectly labels it secondary; the carbon has three attachments.
• C: Wrong numbering (4-hexane) violates lowest number rule for substituents.
• D: Invalid name (4-bromo-5-hexane) and misclassifies as secondary.

Final answer: B