Explanation:

Alright, let’s break this one down:

- Isopentane is a common name for a specific structure within the family of C5H12 hydrocarbons.

- Its structure? Four carbons in a chain, with a methyl group branching off the second carbon. So basically, it’s a “methyl-butane.”

- Here’s the rundown on your options:

- Option 1: butadiene – That’s a totally different molecule (C4H6) with two double bonds; not even a saturated hydrocarbon.

- Option 2: dimethylbutane – That’s a C6 compound, or if you sketch it out as a C4 chain with two methyl groups, it gives you a different arrangement (like neopentane).

- Option 3: 2-methylbutane – This is the IUPAC name for isopentane. A four-carbon chain with a methyl group on carbon 2.

- Option 4: isobutane – That’s C4H10, same idea of branching but one less carbon overall.

- So, isopentane = 2-methylbutane. That’s the real match.