To predict which substance would have a higher boiling point, we need to consider the intermolecular forces present in each substance. The primary intermolecular force in both methane CH4 and ethane C2H6 is London dispersion forces, which are temporary attractive forces due to the random movement of electrons.In general, the strength of London dispersion forces increases with the size and mass of the molecule. Since ethane C2H6 is larger and has a greater molecular mass than methane CH4 , it will have stronger London dispersion forces. As a result, more energy is required to overcome these forces in ethane, leading to a higher boiling point compared to methane.