The circles in the diagrams below represent energy levels in an atom, and the arrows show electron (blue dot) transitions from one energy level to another. (the spacing between circles represents differences in energy: a larger spacing means a greater difference in energy.) assuming that the transitions occur as photons are emitted, rank the atoms based on the photon energy, from highest to lowest. hints

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.