Which among the following statements are connect with respect to adsorption of gases on a solid ? (1) The extent of adsorption is equal to kpn according to freundlich isotherm. (2) The extent of adsorption is equal to kp1n according to freundlich isotherm . (3) The extent of adsorption is equal to (a+bp)ap according to freundlich isotherm . (4) The extent of adsorption is equal to ap(1+bp) according to freundlich isotherm . (5) Freundlich adsorption fails at a low pressure .