Step 1: Understand the Tanks-in-Series Model.
In the Tanks-in-Series model, each tank is modeled as a completely mixed reactor, and increasing the number of tanks \( n \) leads to a more plug-flow-like behavior, reducing the spread of the RTD.
Step 2: Analyze the Variance Trend.
As \( n \) increases, the variance of the residence time distribution (\( \sigma^2_\Theta \)) decreases due to the progressive narrowing of the RTD curve, reflecting less dispersion and more uniform residence times.

Choose the option that correctly matches the items in Group 1 with those in Group 2.

Oil is extracted from mustard seeds having 20 wt% oil and 80 wt% solids, using hexane as a solvent. After extraction, the hexane-free residual cake contains 1 wt% oil. Assuming negligible dissolution of cake in hexane, the percentage oil recovery in hexane is ___________ % (rounded off to the nearest integer).
The residence-time distribution (RTD) function of a reactor (in min−1) is:
\[ E(t) = \begin{cases} 1 - 2t, & \text{if } t \leq 0.5\ \text{min} \\ 0, & \text{if } t > 0.5\ \text{min} \end{cases} \]
The mean residence time of the reactor is _____ min (rounded off to 2 decimal places).