Related Mcqs:

1. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that___________________?

   A. The system comprises of partially miscible liquids
   B. The system comprises of miscible liquids
   C. The system comprises of an azeotrope
   D. On heating, a vapor phase will appear; while on cooling, a solid phase will appear

2. An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) ____________________?

   A. Less number of trays are required
   B. Composition of the residue remains unchanged
   C. More number of trays are required but the residue composition remains unchanged
   D. More number of trays are required and the residue composition is more dilute in methanol

3. A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state ?

   A. Composition of vapors and that of liquid do not vary throughout the column
   B. Reboiler load and condenser load are minimum
   C. The top and bottom compositions are unchanged with and without total reflux
   D. The top and bottom compositions correspond to the maximum enrichment available

4. The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is____________________?

   A. 2
   B. 0.5
   C. 50
   D. 150

5. In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as_____________________?

   A. Ri = Re/(1 – Re)
   B. Ri = (1 – Re)/Re
   C. Ri = Re
   D. Ri = Re/(1 + Re)

6. Total reflux in a distillation operation requires minimum____________________?

   A. Reboiler load
   B. Number of plates
   C. Condenser load
   D. All A., B. and C.

7. A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below: In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is_______________ ?

   A. 0.5
   B. 0.6
   C. 1.0
   D. 2.0

8. For the same process conditions, the reflux ratio of an unlagged distillation column___________________?

   A. Decreases in winter
   B. Increases in winter
   C. Increases in summer
   D. None of these

9. Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.) ?

   A. (1 + Ro) = Ro/Ri
   B. (1 – Ro) = Ro/Ri
   C. (1 + Ri) = Ro/Ri
   D. (1 – Ri) = Ro/Ri

10. What is the reflux ratio at total reflux ?

    A. Zero
    B. Infinity
    C. Unity
    D. Data insufficient