For keyboard navigation, use the up/down arrow keys to select an answer. a) Because the positive charge is on primary and secondary allylic carbocations etc. b) Because the positive charge is on a primary and a tertiary carbon c) Because the positive charge is on a primary and a secondary carbon d) Because the positive charge is on a secondary and a tertiary carbon

b) because the positive charge is on primary and a tertiary carbon

Explanation:

The allylic carbon atom carries positive charge when primary carbon has positive charge. It forms an ion with tertiary carbon atom to form resonance. In secondary carbocation the positive charge is on secondary carbon atom. The atom are attracted and electrons form carbon -  carbon sigma.

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.