$9.$ Continuous contact extractors are preferred for:

$-$ A$.$ Small$-$scale laboratory experiments

$-$ B$.$ Large$-$scale industrial applications

$-$ C$.$ Processes requiring high pressure

$-$ D$.$ Processes using solid$-$liquid extraction

$10.$ Batch extractors are characterized by:

$-$ A$.$ Continuous operation

$-$ B$.$ Handling multiple feeds simultaneously

$-$ C$.$ Periodic operation

$-$ D$.$ Use in only large$-$scale operations

$11.$ The choice of solvent in extraction is mainly based on:

$-$ A$.$ Color of the mixture

$-$ B$.$ Selectivity and affinity towards the solute

$-$ C$.$ Boiling point of the solvent

$-$ D$.$ Price of the solvent

$12.$ Miscible solvent extraction is used when:

$-$ A$.$ The components are easily separated by distillation

$-$ B$.$ The components form azeotropes

$-$ C$.$ The solutes are solids

$-$ D$.$ The phases form an emulsion