Practice Pakistan's most useful MCQs for competitive exams

(NRe . NSc) is termed in mass transfer operation as the ______________ number?

• (A)  Stanton
• (B)  Sherwood
• (C)  Peclet
• (D)  None of these

Answer

Submitted By :Ali Uppal

With lapse of time, the overhead composition of light component in case of batch distillation with constant reflux__________________?

• (A)  Increases
• (B)  Decreases
• (C)  Remain same
• (D)  May increase or decrease; depends on system

Answer

Submitted By :Ali Uppal

The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called__________________?

• (A)  Decoction
• (B)  Percolation
• (C)  Elutriation or elution
• (D)  None of these

Answer

Submitted By :Ali Uppal

The recovery of penicillin from the acidified fermentation broth is done by__________________?

• (A)  Distillation
• (B)  Evaporation
• (C)  Absorption
• (D)  Liquid extraction

Answer

Submitted By :Ali Uppal

Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is _______________ the liquid head available in the downcomer?

• (A)  Less than
• (B)  More than
• (C)  Same as
• (D)  Very much less

Answer

Submitted By :Ali Uppal

Which of the following is an undesirable characteristic for the solvent used in gas absorption ?

• (A)  Low vapor pressure
• (B)  Low viscosity
• (C)  High gas solubility
• (D)  None of these

Answer

Submitted By :Ali Uppal

For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will_____________________?

• (A)  Increase
• (B)  Decrease
• (C)  Remain same
• (D)  Data insufficient, can’t be predicted

Answer

Submitted By :Ali Uppal

A liquid mixture contains 30% o-xylene, 60% p-xylene and 10%. m-xylene (all percentages in w/w). Which of the following statements would be true in respect of this mixture ?

• (A)  The mixture exhibits an azeotrope at 101.3 kPa
• (B)  The composition of the mixture, in percent by volume is: o-xylene 30, p-xylene 60. and mxylene 10
• (C)  The composition of the mixture in mole percent is: o-xylene 30, p-xylene 60 and m-xyoene 10
• (D)  The mixture contain optical isomers

Answer

Submitted By :Ali Uppal

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of_______________________?

• (A)  Area between operating line and 45° diagonal x-y diagram
• (B)  Condenser and reboiler surfaces
• (C)  Tower cross-section
• (D)  None of these

Answer

Submitted By :Ali Uppal

Which of the following assumes constant molal vaporisation and overflow ?

• (A)  McCabe-Thiele method
• (B)  Ponchan-Savarit method
• (C)  Enthalpy concentration method
• (D)  Plate absorption column

Answer

Submitted By :Ali Uppal