The isomeric relationship between 2-pentene and 2-methylbutene is that they are positional isomers. Positional isomers are compounds with the same molecular formula but different connectivity of atoms due to the difference in the position of the functional group.Structural difference:2-Pentene has the molecular formula C5H10 and is an alkene with a double bond between the second and third carbon atoms. Its structure can be represented as CH2=CH-CH2-CH3.2-Methylbutene also has the molecular formula C5H10 and is an alkene with a double bond between the second and third carbon atoms. However, it has a methyl group CH3 attached to the second carbon atom, making its structure CH3-C CH3 =CH-CH3.Physical properties:The physical properties of these two positional isomers may vary slightly due to the difference in their structures.1. Boiling point: The boiling point of 2-pentene is around 36C, while the boiling point of 2-methylbutene is around 38C. The slight difference in boiling points can be attributed to the difference in their molecular structures and the resulting weak intermolecular forces.2. Density: The density of 2-pentene is approximately 0.641 g/mL, while the density of 2-methylbutene is around 0.662 g/mL. The difference in densities can be attributed to the difference in their molecular structures and the way the molecules pack together.3. Stability: Both 2-pentene and 2-methylbutene are relatively stable due to the presence of the double bond. However, 2-methylbutene may be slightly more stable due to the presence of the methyl group, which can provide some steric hindrance and reduce the reactivity of the double bond.4. Reactivity: Both compounds are alkenes and will undergo similar reactions, such as electrophilic addition and oxidation reactions. However, the reactivity of the two compounds may differ slightly due to the presence of the methyl group in 2-methylbutene, which can affect the electron density around the double bond and influence the compound's reactivity.