In 1909, ernest rutherford performed an experiment to explore the atomic structure. in his experiment, he projected high-speed positively charged α‎ particles onto a thin gold foil. he found that all α‎ particles did not follow the same path. many particles passed through the foil without any scattering, implying that most of the space in an atom is empty. some particles were scattered at a large angle, and very few of them scattered back in the direction from which they had come. based on these observations, rutherford proposed an atomic model, which is known as rutherford’s atomic model

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.