A solution consists of a mixture of benzene and toluene and is allowed to come to equilibrium with its vapor. The vapor is then condensed and found to contain equal moles of each component. Calculate the composition (mole percent) of benzene in the original solution. The vapor pressures of pure benzene and toluene at this temperature are 750. torr and 300. torr respectively.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.

you need to have a picture of the atom that way we can answer it