Stoichiometry problems which give a known amount of one reactant and solve for an amount of product frequently state that there is "an excess" or "plenty" of the reactant(s) not given. (For example, in the equation 2Na + 2H2O → 2NaOH + H2, how many grams of sodium hydroxide are produced from 3.0 mol of sodium with an excess of water?) Why is it necessary to know that there is an excess of these reactant(s)?

output?

explanation:

the solar system used to have much dust particles option no d

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.