36) The extraction is a recommended separation med when a) Distillation is too expensive b) The materials are nonvolatile c) Heat-sensitive materials are involved d) All of the above 37) in the continuous extraction experiment, the water entered the colum a) The top of the column b) The bottom of the column e) At the middle of the column d) None if the above 38) The bottom layer in the extraction column was a) Raffinate layer b) Extract layer c) Feed layer d) None of the above 39) One of the following is true about the liquid-liquid extraction experiment a) Propionic acid is the solute and raffinate is rich in it b) Propionic acid is the solute and the extract is rich in it c) Trichloroethylene is the solute and the raffinate u rich in it. d) Trichloroethylene is the solute and the extract is rich in it 40) The following term in the liquid-liquid extraction experiment (x-x'), (x-x'). (x-x) (-X (ln (Y CHE COMITEE represents: a) The main driving force for mass transfer b) The height of theoretical stage c) The height of actual stage d) Number of theoretical stages