There are five structural isomers for the molecular formula C6H14. These isomers are different in the arrangement of their carbon and hydrogen atoms, which leads to differences in their physical properties such as boiling points, melting points, and densities. The five structural isomers are:1. n-Hexane Hexane : This is a straight-chain alkane with six carbon atoms connected in a row. The structure is CH3-CH2-CH2-CH2-CH2-CH3. It has a boiling point of 69C and a melting point of -95C.2. 2-Methylpentane Isohexane : In this isomer, one of the hydrogen atoms on the second carbon atom is replaced by a methyl group CH3 . The structure is CH3-CH CH3 -CH2-CH2-CH3. It has a boiling point of 60C and a melting point of -153C.3. 3-Methylpentane: In this isomer, one of the hydrogen atoms on the third carbon atom is replaced by a methyl group CH3 . The structure is CH3-CH2-CH CH3 -CH2-CH3. It has a boiling point of 63C and a melting point of -140C.4. 2,2-Dimethylbutane Neohexane : In this isomer, two of the hydrogen atoms on the second carbon atom are replaced by two methyl groups CH3 . The structure is CH3-C CH3 2-CH2-CH3. It has a boiling point of 49C and a melting point of -129C.5. 2,3-Dimethylbutane: In this isomer, one of the hydrogen atoms on the second carbon atom and one of the hydrogen atoms on the third carbon atom are replaced by methyl groups CH3 . The structure is CH3-CH CH3 -CH CH3 -CH3. It has a boiling point of 58C and a melting point of -131C.The differences in physical properties among these isomers can be attributed to their molecular structures. Straight-chain alkanes like n-hexane generally have higher boiling points due to their larger surface area, which leads to stronger London dispersion forces a type of van der Waals force between the molecules. Branched alkanes like the other isomers have more compact structures, which result in weaker London dispersion forces and lower boiling points. Melting points and densities also vary due to differences in molecular packing and intermolecular forces.