Final answer:
Hexane, with its higher molecular weight and larger surface area, has the highest boiling point, followed by isopentane, and finally neopentane, which has the most compact structure and the lowest boiling point.
Step-by-step explanation:
When ranking molecular boiling points, it is important to consider the molecular mass and structure of the compounds, primarily because the intermolecular forces involved are usually London dispersion forces for nonpolar molecules like alkanes. These forces are stronger with increasing molecular weight and surface area, allowing for more significant interactions between molecules.
Given the alkanes isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and hexane, we can rank their boiling points based on their molecular masses and structural compactness. Hexane is a straight-chain alkane with a higher molecular weight and larger surface area, leading to stronger London dispersion forces and the highest boiling point among the given compounds. Isopentane, having a branched chain, has somewhat more surface area than neopentane but less than hexane, positioning it in the middle in terms of boiling points. Neopentane has the most compact structure with the least surface area exposed to the intermolecular forces, giving it the lowest boiling point.
Therefore, we can arrange the given compounds in order of boiling points from the highest to the lowest as follows: hexane > isopentane > neopentane.