In Langmuir treatment of adsorption,

• A. whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule.
• B. whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site.
• C. all the adsorption does not take place by the same mechanism.
• D. extent of adsorption is more than one complete monomolecular layer on the surface.