Solution:
{\bf Single choice}\\
Please choose the $\uline{\mbox{\bf incorrect}}$ description.
\begin{parts}
\part For overall effectiveness factor ($\Omega$), the molar rate of mass transfer to the surface, $M_A$ is equal to the net (total) rate of reaction {\it on} and {\it within} the pellet.
\part Overall effectiveness factor ($\Omega$) can be defined as actual overall rate of reaction / rate that would result if the entire surface were exposed to the bulk conditions, $C_{Ab}$, $T_b$.
\part The effective diffusivity $D_e$ accounts for the fact that not all of the area normal to the direction of the flux is available for the molecules to diffuse.
\part Large values of the Thiele modulus indicate surface reaction controls and significant amount of the reactant diffuses well into the pellet interior without reacting.
\end{parts}
