Which name refers to the branched-chain alkane with formula C4H10?

• A. Butane
• B. Pentane
• C. Methyl propane
• D. Ethane

Answer: (C)

Understanding how alkanes are named helps you spot isomers with the same formula but different structures. For four carbons, there are two possibilities: a straight-chain form and a branched form. The branched one has a methyl group attached to a propane chain, giving a total of four carbons, so its name points to a branch on propane. That structure is best described as methyl propane, which is more precisely 2-methylpropane. This is also known as isobutane. Its formula is C4H10, matching the question’s requirement.

In contrast, the straight-chain four-carbon alkane is butane (unbranched), still with the same formula but not branched. The other options refer to different molecules: ethane has two carbons, and pentane has five, so they don’t fit the given formula.