A metallic surface is covered by a monomolecular layer of N~ organic molecules in a square array. Each adsorbed molecule can exist in two steric configurations, designated as oblate and prolate. Both configurations have the same energy. However two nearest neighbor molecules mechanically interfere if, and only if, both are oblate. The energy associated with such an oblate--oblate interference is ε (a positive quantity). Calculate a reasonable estimate of the number of molecules in each configuration at temperature T.