mass transfer

please solve it

aza 1) The SI units of the diffusion coefficient is given by: a) /sec b) cm/sec c) m/sec 2) The diffusion process is a mass transfer operation where mass is transferred from: a) High concentration point to low concentration point. b) Low concentration point to high concentration point. e) None of the above. 3) The Molar flux of a substance being transferred can be expressed in the units of: a) Mass/(area-time) le kg/m- sec b) Moles/(area-time).i.e Kgmole/m-sec 4) Molecular diffusivity of a liquid: a) increases with temperature. b) decreases with temperature. c) may increase or decrease with temperature, d) is independent of temperature. 5) Gas A diffuses to the surface of a catalyst where it is converted into B according to the reaction 3A B. Product B diffuses back. The ratio of the molar flux of A to B at steady state is: a) -3 b) -1/3 c)3 d)1/3 6) The diffusion coefficient in a binary gas mixture at low pressure varies with pressure as: a) P b) P2 c)/P d) independent of P 7) Fick's second law of diffusion in one dimension can be written as: a) L=-D ) ) ) = -D. C's) OJA --DO) d)) = Das (CSA) 8) Knudsen diffusion coefficient depends on: a) temperature and it is independent of pressure. b) pressure and it is independent of temperature. c) pressure and temperature. d) independent on temperature and pressure. 9) The variation of the Knudsen diffusion coefficient (DK) with temperature (T) follows: a) DKAAT c) Dk a 1/2 d) DKAQ T2 10) The units of permeability are: m2 kmo! kPa m b) d) sec m?sec m masec (kPa/m) 11) For one-dimensional diffusion in a wide (x direction), deep (y direction) slab, the molar flux NA Z varies with Z? a)Naz = zero b) Naz = constant c) Naz=f(z) 12) In a cylindrical geometry, for one-dimensional diffusion (long tube, symmetry assumed) in the radial direction, how does the flux NA 1 a) Narar b) Nar xr c)Nara d)Nar * f) 13) In the spherical geometry, for one-dimensional diffusion (and symmetry assumed) in the radial direction, how does the flux NA 1 a) Narar c) Nara d)NA (1) r 14) Liquid diffusivity is in the range of (0.5x109 - 1x109 m/sec, while gas diffusivity is in the range of (10.10 m/sec. a) True b) False 15) Fick's law of diffusion is given by the formula: a) JA--DAB AWA b) JA --DABACAC)JA --DA dC/dz d) All of these 16) The driving force of mass transfer is: a) The temperature gradient. b) The concentration gradient. c) The pressure gradient b) D ? b) Nar & 3 / 4