$1.$ What is the significance of the minimum solvent flow rate in an absorption process?

$-$ A$)$ It determines the maximum gas flow rate that can be treated.

$-$ B$)$ It is the lowest flow rate at which the desired separation efficiency can be achieved.

$-$ C$)$ It indicates the maximum efficiency of the solvent.

$-$ D$)$ It defines the optimal temperature for the operation.

$2.$ The absorption factor $($AF$)$ is defined as the ratio of:

$-$ A$)$ Gas flow rate to solvent flow rate.

$-$ B$)$ Solvent flow rate to gas flow rate.

$-$ C$)$ Gas phase mass transfer coefficient to liquid phase mass transfer coefficient.

$-$ D$)$ Solvent capacity to gas flow rate.

$3.$ The Height Equivalent to a Theoretical Plate $($HETP$)$ in a packed column is used to:

$-$ A$)$ Estimate the total height of the column.

$-$ B$)$ Determine the diameter of the column.

$-$ C$)$ Calculate the number of theoretical stages.

$-$ D$)$ Measure the efficiency of packing material.

$4.$ The number of transfer units $($NTU$)$ concept is crucial for:

$-$ A$)$ Determining the solvent flow rate.

$-$ B$)$ Calculating the height of an absorption column.

$-$ C$)$ Estimating the gas flow rate.

$-$ D$)$ Selecting the type of packing material.