In an experimental wetted-wall column, pure carbon dioxide is absorbed in water. The mass transfer rate is calculated using the penetration theory, application of which is limited by the fact that the concentration should not reach more than 1 per cent of the saturation value at a depth below the surface at which the velocity is 95% of the surface velocity. What is the maximum length of column to which the theory can be applied if the flow rate of water is 3 cc/s.cm of perimeter? Viscosity of water = 0.001 Ns/m2 Diffusivity of CO2 in water=1.5x109 m²/s.