POSSIBLE POINTS: 23.53 Determine how the given change will affect the rate of a chemical reaction. The answer choices are:
(a) Increases the rate
. (b) Decreases the rate
(c) No change
6. A decrease in temperature
B
7. A decrease in activation energy for the reaction
(adding a catalyst)
A
8. An increase in the reactant concentration
9. An increase in the surface area of one of the
reactants in a reaction (larger size)
:: A
:: B

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.