100 mL of an aqueous solution containing 0.0004 mM n-nonane is placed in a closed cylindrical vessel of inner diameter 5 cm and total height 10 cm. What fraction of n-nonane is present at the air-water interface in this system? If the total height of the vessel is reduced to 5.5 cm, what is the adsorbed fraction? Assume that n-nonane does not adsorb to the vessel wall.