List of top Mass Transfer Questions on Molecular diffusion in fluids

Consider steady-state diffusion in a binary A-B liquid at constant temperature and pressure. The mole-fraction of A at two different locations is 0.8 and 0.1. Let $N_{A1}$ be the diffusive flux of A calculated assuming B to be non-diffusing, and $N_{A2}$ be the diffusive flux of A calculated assuming equimolar counter-diffusion. The quantity $\frac{(N_{A1} - N_{A2})}{N_{A1}} \times 100$ is $\underline{\hspace{2cm}}$ (rounded off to one decimal place).

Consider two stationary spherical pure water droplets of diameters $ d_1 $ and $ 2d_1 $. CO$_2$ diffuses into the droplets from the surroundings. If the rate of diffusion of CO$_2$ into the smaller droplet is $ W_1 $ mol s$^{-1}$, the rate of diffusion of CO$_2$ into the larger droplet is

As shown in the figure below, air flows in parallel to a freshly painted solid surface of width 10 m, along the z-direction. The equilibrium vapor concentration of the volatile component A in the paint, at the air-paint interface, is $ C_{A,i} $. The concentration $ C_A $ decreases linearly from this value to zero along the y-direction over a distance $ \delta $ of 0.1 m in the air phase. Over this distance, the average velocity of the air stream is 0.033 m s$^{-1}$ and its velocity profile $ v_z(y) $ is given by \[ v_z(y) = 10 y^2 \] where $ y $ is in meter. Let $ C_{A,m} $ represent the flow averaged concentration. The ratio of $ C_{A,m} $ to $ C_{A,i} $ is $\underline{\hspace{1cm}}$ (round off to 2 decimal places).