$45.$ The absorption factor's significance in the design of an absorption system lies in its ability to:

$-$ A$)$ Determine the optimal operating temperature and pressure.

$-$ B$)$ Indicate the proportion of gas absorbed by the solvent, thereby affecting the design and solvent flow rate.

$-$ C$)$ Predict the lifespan of the packing material.

$-$ D$)$ Calculate the minimum diameter of the column.

$46.$ Analytical methods for determining the number of ideal stages in an absorption column are preferred when:

$-$ A$)$ The process is at a pilot scale, and data is limited$.$

$-$ B$)$ Detailed and accurate process specifications are required for large$-$scale operations.

$-$ C$)$ The designer prefers a quick estimation over accuracy.

$-$ D$)$ The equilibrium data between the gas and liquid phases is unknown.

$47.$ The overall gas phase mass transfer coefficient $($Kga$)$ plays a crucial role in determining:

$-$ A$)$ The type of packing material to be used in the column.

$-$ B$)$ The rate at which the gas component is absorbed by the liquid solvent.

$-$ C$)$ The thermal efficiency of the process.

$-$ D$)$ The viscosity of the liquid solvent.

$48.$ In designing an absorption column, the height of a transfer unit $($HTU$)$ is significant because it:

$-$ A$)$ Indicates the column's ability to handle fluctuations in gas flow rates.

$-$ B$)$ Determines the total height of the column needed to achieve the desired separation efficiency.

$-$ C$)$ Reflects the solvent's capacity to absorb specific pollutants.

$-$ D$)$ Determines the pressure drop per unit height of the column.