Fatty acids spread spontaneously on water to form a monomolecular film. A benzene solution containing 0.10 mm cubed of stearic acid is dropped into a tray full of water. The acid is insoluble in water, but spreads on the surface to form a continuous film covering an area of 400. cm squared after all of the benzene has evaporated. What is the average film thickness in (a) nanometers and (b) angstroms?