Which term represents the fixed proportion of elements in a compound.

The correct answer is Chemical Formula.

Explanation:

The chemical formula of a compound represents the fixed proportion of elements present in the same or the number of atoms forming a molecule. This formula can also give us information about how these atoms are joined by chemical bonds and even their distribution in space.

Have a nice day!

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.