A sphere of solid salt, 25mm in diam and mass m=0.36kg is placed in a large volume of stagnant water (25C). Calculate the rate of dissolution (kg/s). The diffusion coefficient of the solute in waler at 25C=109m2/s and the equilibrium saturated solubility of the salt in water at 25C is 380kg/m3. Find, the time required (days) for Complete dissolution of the sphere