Two forms of butane known as n-butane and iso-butane form an equilibrium according to the reaction n-butane (g) iso-butane (g) If the equilibrium constant for this reaction is 23,which set of concentrations listed below represents an equilibrium of these two compounds? 3) (n-butane] 0.04 M [iso-butane] = 0.27 M In-butane] 0.45 M liso-butane] 0.22 M In-butane] 0.23 M liso-butane] 0,01 M In-butane] 0.02 M fiso-butane] 0.46 M