The air in a bicycle tire is bubbled through water and collected at 25 degrees C. If the total volume of gas collected is 5.45 L at a temperature of 25 degree C and a pressure of 745 torr, how many moles of gas were in the bicycle tire

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

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.