Related Questions

A first order reaction A → B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by
A Diffusion within the pellet
B Reaction
C External mass transfer
D None of the above
If Thiele modulus is __________ , then the pore diffusion resistance in a catalyst may be considered as negligible.
A 0
B ∞
C > 0.5
Effectiveness factor of a catalyst pellet is a measure of the __________ resistance.
A Pore diffusion
B Gas film
C Chemical reaction
D None of these
Which of the following factors control the deactivation of a porous catalyst pellet?
A Decay reactions
B Pore diffusion
C Form of surface attack by poison
D All of the above
If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst
A Porosity is very important
B Porosity is of less importance
C Internal surface area is utilised efficiently
D None of these
If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process'. The diffusivity under this condition is called 'Knudsen diffusivity', which is affected by the
A Pressure
B Temperature
C Both A & B
D Neither A nor B
Bulk diffusion in catalyst pore __________ with increase in pressure.
A Increases
B Decreases
C Remains unchanged
D Increases exponentially
If the modulus of elasticity for a given material is twice its modulus of rigidity, then bulk modulus is equal to
A 2C
B 3C
C $$\frac{{2{\text{C}}}}{3}$$
D $$\frac{{3{\text{C}}}}{2}$$
The relation between Young's modulus (E), shear modulus (C) and bulk modulus (K) is given by
A $${\text{E}} = \frac{{3{\text{KC}}}}{{3{\text{K}} + {\text{C}}}}$$
B $${\text{E}} = \frac{{6{\text{KC}}}}{{3{\text{K}} + {\text{C}}}}$$
C $${\text{E}} = \frac{{9{\text{KC}}}}{{3{\text{K}} + {\text{C}}}}$$
D $${\text{E}} = \frac{{12{\text{KC}}}}{{3{\text{K}} + {\text{C}}}}$$
Overall rate of reaction in a heterogenous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of catalyst, if it does not entail a chain mechanism.
A Proportional to
B Independent of
C Inversely proportional to
D Proportional to the square of

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