Hexane, being the largest molecule among ethane, propane, butane, and pentane, has the highest boiling point due to stronger London dispersion forces.
The question asks which compound among ethane, propane, butane, pentane, and hexane has the highest boiling point. All these compounds are alkanes and nonpolar, meaning that the dominant intermolecular forces affecting their boiling points are London dispersion forces. These forces typically increase with molecular mass, leading to higher boiling points for larger molecules. Therefore, given the five alkanes, the one with the highest molecular mass will have the highest boiling point. Hexane, being the largest alkane with the most carbon atoms in the series mentioned, will have the strongest London dispersion forces and therefore the highest boiling point.
So, as the size of an alkane increases, so does its boiling point due to stronger London dispersion forces. The alkane with the greatest number of carbon atoms here is hexane, and thus hexane is expected to have the highest boiling point among the compounds listed.