A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t = 0 for the cubic to spherical tablet is___________________?

Related Mcqs:

1. A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids)) ?

   A. M(Xo – XF)
   B. M(Xo/XF)
   C. M ln(Xo/XF)
   D. MXo ln(Xo/XF)

2. A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids))_____________?

   A. M(Xo – XF)
   B. M(Xo/XF)
   C. M ln(Xo/XF)
   D. MXo ln(Xo/XF)

3. For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is___________________?

   A. Calculated
   B. Unknown
   C. Known
   D. Not required

4. Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is___________________?

   A. Insoluble in the liquid
   B. Soluble in the liquid
   C. Non-ideal in nature
   D. At a fixed temperature

5. According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity) ?

   A. D
   B. D2
   C. D0.5
   D. 1/D

6. JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by___________________?

   A. Nsh = 2
   B. Nst = 2
   C. Nsc = 2
   D. None of these

7. The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same system is_______________________?

   A. 100
   B. 10
   C. 5
   D. 1

8. The mass transfer co-efficient for a solid sphere of radius ‘a’ dissolving in a large volume of quiescent liquid, in which „D’ is the diffusivity of solute, is _____________________?

   A. D/a
   B. D/2a
   C. Proportional to √D
   D. Dependent on the Reynolds number

9. In a single stage extraction process, 10 kg of pure solvent S (containing no solute A) is mixed with 30 kg of feed F containing A at a mass fraction xf = 0.2. The mixture splits into an extract phase E and a raffinate phase R containing A at xB = 0.5 and xR = 0.05 respectively. The total mass of the extract phase is (in Kg) ?

   A. 6.89
   B. 8.89
   C. 10
   D. 8.25

10. At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?

    A. 0.0
    B. 0.2
    C. 0.4
    D. 1.0