Select the correct IUPAC name for the following branched chain alkane: $C_5{H}_{12}$ with a methyl group attached to the second carbon of the main chain.

• A. Isopentane
• B. 3-Methylbutane
• C. 2-Methylbutane
• D. Pentane

Answer: (C)

Verified step by step guidance

1. Identify the longest continuous carbon chain in the molecule. Since the molecular formula is \(C_5H_{12}\), the longest chain contains 4 carbons (butane) with one additional methyl group attached.
2. Number the carbon atoms in the main chain from the end nearest to the substituent (the methyl group) to give the substituent the lowest possible number. This means the methyl group is attached to carbon 2.
3. Name the substituent group attached to the main chain. In this case, it is a methyl group (\(-CH_3\)).
4. Combine the substituent name and position number with the name of the main chain. The substituent position is indicated by a number followed by a hyphen, then the substituent name, and finally the main chain name.
5. Write the full IUPAC name as \$2$-Methylbutane, indicating a methyl group attached to the second carbon of a butane chain.