Would having different atmospheric pressures have an effect on the accuracy of gas laws? If so, which planets would be the most reliable and which would be the least?

With the changes in atmospheric pressure, the gas laws also change accordingly, that is, the Charle's law, the Boyle's law, the Ideal Gas Law, and the Gay-Lussac's law changes with the change in atmospheric pressure. Therefore, the planets, which exhibits the constant value of atmospheric pressure will be more reliable, and those possessing different atmosphere or no atmosphere will be the least reliable.

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.