.A vertical glass tube 3 mm in diameter is filled with liquid toluene to a depth of 20mm from the top openend. After 275 hrs at 39.4 C and a total pressure of 760 mm Hg the level has dropped to 80 mm from the top. Calculate the value of diffusivity. Data: vapor pressure of toluene at 39.4 C = 7.64 kN / m2 density of liquid toluene = 850 kg/m3 Molecular weight of toluene = 92