2-butene and 1-butene are positional isomers. Positional isomers are compounds that have the same molecular formula but differ in the position of the functional group within the molecule.1-butene: CH2=CH-CH2-CH32-butene: CH3-CH=CH-CH3Physical properties:1. Boiling point: 1-butene has a boiling point of -6.3C, while 2-butene has a boiling point of -3.7C. The difference in boiling points is due to the difference in the position of the double bond, which affects the electron distribution and intermolecular forces in the molecules.2. Density: Both isomers have similar densities, with 1-butene having a density of 0.62 g/mL and 2-butene having a density of 0.63 g/mL.Chemical properties:1. Reactivity towards addition reactions with hydrogen hydrogenation : Both 1-butene and 2-butene undergo hydrogenation to form butane. However, they differ in their reactivity towards hydrogenation due to the difference in the position of the double bond.1-butene: CH2=CH-CH2-CH3 + H2 CH3-CH2-CH2-CH3 butane 2-butene: CH3-CH=CH-CH3 + H2 CH3-CH2-CH2-CH3 butane In 1-butene, the double bond is located at the terminal carbon, while in 2-butene, the double bond is located between the two central carbons. The terminal double bond in 1-butene is more accessible to the hydrogen molecule, making it more reactive towards hydrogenation than 2-butene. Additionally, the steric hindrance in 2-butene due to the presence of two methyl groups adjacent to the double bond makes it less reactive towards hydrogenation compared to 1-butene.In summary, 2-butene and 1-butene are positional isomers that differ in the position of the double bond within the molecule. This difference in the position of the double bond affects their physical properties, such as boiling points, and their chemical reactivity towards addition reactions with hydrogen. 1-butene is more reactive towards hydrogenation due to the terminal double bond, which is more accessible to the hydrogen molecule and has less steric hindrance compared to the double bond in 2-butene.