Final answer:
The correct name of the organic molecule with a 5-carbon chain and a methyl group on the third carbon is 3-methylpentane.
Step-by-step explanation:
The correct name for the molecule in question is 3-methylpentane. When naming an organic molecule, it is crucial to first identify the longest chain of carbon atoms, as it forms the base of the name. In your case, the longest carbon chain has five carbon atoms, which corresponds to pentane. The molecule also has a one-carbon substituent located on the third carbon atom, which is named as a methyl group.
Therefore, the name of the molecule becomes 3-methylpentane. It's important to note that the number 3 indicates the carbon on which the methyl group is attached, with the numbering of the carbons starting from the end closest to the substituent to get the lowest possible numbers. The nomenclature of such molecules is very specific, and it ensures that each unique molecular structure can be accurately identified.