Alkenes, alkynes, and alkanes are all hydrocarbons, which means they are composed of hydrogen and carbon atoms. However, they differ in their structure and physical properties due to the type of bonding between the carbon atoms.1. Structure and Bonding:- Alkanes: These are saturated hydrocarbons with single bonds sigma bonds between the carbon atoms. They have the general formula CnH2n+2. An example is methane CH4 .- Alkenes: These are unsaturated hydrocarbons containing a carbon-carbon double bond one sigma bond and one pi bond . They have the general formula CnH2n. An example is ethene C2H4 .- Alkynes: These are unsaturated hydrocarbons containing a carbon-carbon triple bond one sigma bond and two pi bonds . They have the general formula CnH2n-2. An example is ethyne C2H2 .2. Physical Properties:- Boiling Point: Alkanes generally have higher boiling points than alkenes and alkynes of similar molecular weight. This is due to the increased number of electrons in alkanes, which leads to stronger London dispersion forces a type of van der Waals force . As the molecular weight increases, the boiling point increases for all three types of hydrocarbons. For example, the boiling points of propane alkane, C3H8 , propene alkene, C3H6 , and propyne alkyne, C3H4 are -42C, -47.6C, and -23.2C, respectively.- Melting Point: The melting points of alkanes, alkenes, and alkynes follow a similar trend as their boiling points. Alkanes generally have higher melting points than alkenes and alkynes due to stronger London dispersion forces. For example, the melting points of ethane alkane, C2H6 , ethene alkene, C2H4 , and ethyne alkyne, C2H2 are -183.3C, -169.2C, and -80.8C, respectively.- Density: The densities of alkanes, alkenes, and alkynes are generally less than that of water, which means they float on water. As the molecular weight increases, the density increases for all three types of hydrocarbons. However, there is no significant difference in density between alkanes, alkenes, and alkynes of similar molecular weight.- Solubility: Alkanes, alkenes, and alkynes are all nonpolar molecules, which means they are insoluble in polar solvents like water. They are, however, soluble in nonpolar solvents such as hexane or carbon tetrachloride.- Reactivity: Alkanes are relatively unreactive due to the strong carbon-carbon single bonds. Alkenes and alkynes are more reactive because of the presence of double and triple bonds, respectively. The pi bonds in alkenes and alkynes are more susceptible to reactions such as addition reactions, hydrogenation, and halogenation.In summary, alkenes and alkynes differ from alkanes in their structure, bonding, and reactivity. They also have slightly lower boiling and melting points than alkanes of similar molecular weight. However, their densities and solubilities are quite similar.