Practice Pakistan's most useful MCQs for competitive exams

At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?

• (A)  0.0
• (B)  0.2
• (C)  0.4
• (D)  1.0

Answer

Submitted By :Ali Uppal

In a counter-current extractor, as the axial mixing increases, the extraction efficiency______________________?

• (A)  Increases
• (B)  Decreases
• (C)  Remains unchanged
• (D)  Depends on the pressure of the system

Answer

Submitted By :Ali Uppal

In saturated gas, the__________________?

• (A)  Vapour is in equilibrium with the liquid at the gas temperature
• (B)  Vapour is in equilibrium with the liquid at the room temperature
• (C)  Partial pressure of vapour equals the vapour pressure of the liquid at room temperature
• (D)  None of these

Answer

Submitted By :Ali Uppal

Berl saddle made of carbon cannot be used for ___________________?

• (A)  Alkalis
• (B)  SO2
• (C)  H2SO4
• (D)  Oxidising atmosphere

Answer

Submitted By :Ali Uppal

For achieving rapid drying rate in a spray dryer, the diameter of the particles in the feed should be in the range of _______________ microns (1 mm = 1000 microns)?

• (A)  1-5
• (B)  10-60
• (C)  200-300
• (D)  > 500

Answer

Submitted By :Ali Uppal

If G = insoluble gas in gas stream and L = non-volatile solvent in liquid stream, then the slope of the operating line for the absorber is___________________?

• (A)  L/G
• (B)  G/L
• (C)  Always < 1
• (D)  None of these

Answer

Submitted By :Ali Uppal

Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the _______________ number?

• (A)  Schmidt
• (B)  Sherwood
• (C)  Peclet
• (D)  Stanton

Answer

Submitted By :Ali Uppal

Physical absorption is__________________?

• (A)  An irreversible phenomenon
• (B)  A reversible phenomenon
• (C)  Accompanied by evolution of heat
• (D)  Both

Answer

Submitted By :Ali Uppal

Ion exchange process is similar to___________________?

• (A)  Absorption
• (B)  Adsorption
• (C)  Extraction
• (D)  Leaching

Answer

Submitted By :Ali Uppal

Only small amount of evaporation of water produces large cooling effects because of its___________________?

• (A)  Large latent heat
• (B)  Low viscosity
• (C)  Small latent heat
• (D)  None of these

Answer

Submitted By :Ali Uppal