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WorksheetsLIQUID LIQUID EXTRACTION
Total questions: 15
Worksheet time: 8mins
In liquid-liquid extraction, if the selectivity is unity, then
(a) separation of the constituents is most effective
(b) no separation is possible
(c) amount of solvent requirement is minimum
(d) solvent flow rate should be very high
Which of the following is most suitable for extraction from a system having very low density difference?
(a) mixer-settler extractor
(b) centrifugal extractor
(c) pulsed extraction column
(d) packed extraction column
Radioactive nuclear wastes are treated in
(a) mixer-settler extractor
(b) rotating disc contactor
(c) pulsed extractor
As axial mixing increases in a counter-current extractor, the extraction efficiency
(a) increases
(b) decreases
(c) remains unchanged
Selectivity of a solvent for extraction operation
(a) is analogous to relative volatility in distillation practice
(b) must be less than unity
(c) is 0.5 at the plait point
(d) none of these
In liquid-liquid extraction, as the temperature increases, the area covered by the bimodal curve
(a) decreases
(b) increases
(c) remains unchanged
(d) none of these
Operating pressure for liquid extraction should be
(a) sufficiently high to maintain completely condensed system
(b) below the vapour pressures of all the components
(c) equal to the vapour pressure of the most volatile component
(d) equal to the vapour pressure of the least volatile component
During distribution of a solute between two partially miscible solvents, the selectivity at the plait point is
(a) zero
(b 1.0
(c) less than zero
(d) very large
For solvent economy in liquid extraction, the distribution coefficient must be
(a) less than one
(b) equal to one
(c) greater than one
(d) as large as possible
Which of the following operations is more economical for concentration of acetic acid from very dilute aqueous solution?
(a) evaporation
(b) solvent extraction
(c) atmospheric distillation
(d) drying
Heat sensitive material with very high latent heat of vaporisation may be economically separated by
(a) distillation
(b) evaporation
(c) liquid extraction
(d) absorption
In ternary liquid equilibria, the apex of the equilateral triangular diagram represents
(a) an insoluble binary system
(b) a ternary mixture
(c) a binary mixture
(d) a pure component
For fractionation of crude residum, the ROSE process employs supercritical
(a) propane
(b) butane
(c) pentane
(d) hexane
The temperature of a supercritical fluid should be above its
(a) freezing point
(b) boiling point
(c) critical point
(d) none of these
The number of stages required for a given amount of extraction with a given amount of solvent in continuous cross-current multistage extraction is
(a) equal to the number of stages required in continuous counter-current multistage extraction
(b) more than the number of stages required in continuous counter-current multistage extraction
(c) less than the number of stages required in continuous counter-current multistage extraction
