A tube has a length of 0.040 m and a cross-sectional area of 3.8 × 10–4 m2. The tube is filled with a solution of sucrose in water. The diffusion constant of sucrose in water is 5.0 × 10–10 m2/s. A difference in concentration of 4.1 × 10–3 kg/m3 is maintained
between the ends of a tube. How much time is required for 6.7 × 10–13 kg of sucrose to be transported through the tube?