Practice Pakistan's most useful MCQs for competitive exams

The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force) ?

• (A)  Kc = Kp = Km
• (B)  Kc = Kp/RT = Km . RT/P
• (C)  Kc = Kp . RT = Km . RT/p
• (D)  None of these

Answer

Submitted By :Ali Uppal

The temperature of water cooled in cooling tower is always _________________ temperature of entering air?

• (A)  More than the wet bulb
• (B)  Less than the wet bulb
• (C)  Equal to the wet bulb
• (D)  Equal to the dry bulb

Answer

Submitted By :Ali Uppal

Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant____________________?

• (A)  Humidity
• (B)  Velocity
• (C)  Temperature
• (D)  All

Answer

Submitted By :Ali Uppal

With the lowering of equilibrium pressure, at a given temperature, the amount of adsorbate on the adsorbent______________________?

• (A)  Increases
• (B)  Decreases
• (C)  Remain same
• (D)  Either

Answer

Submitted By :Ali Uppal

In liquid extraction, if the selectivity is unity, then___________________?

• (A)  Separation of the constituents is the most effective
• (B)  No separation will occur
• (C)  Amount of solvent required will be minimum
• (D)  Solvent flow rate should be very low

Answer

Submitted By :Ali Uppal

Mass transfer co-efficient is directly proportional to DAB according to the __________ theory?

• (A)  Film
• (B)  Penetration
• (C)  Surface-renewal
• (D)  None of these

Answer

Submitted By :Ali Uppal

___________________ extractor uses centrifugal force for separating the two phases?

• (A)  Treybal
• (B)  Scheibel
• (C)  Podbielniak
• (D)  None of these

Answer

Submitted By :Ali Uppal

The operating cost of a distillation column at minimum reflux ratio is____________________?

• (A)  Minimum
• (B)  Maximum
• (C)  Infinite
• (D)  Zero

Answer

Submitted By :Ali Uppal

The most efficient cooling tower out of the following is_____________________?

• (A)  Induced draft
• (B)  Forced draft
• (C)  Natural draft
• (D)  Atmospheric

Answer

Submitted By :Ali Uppal

The main reason for dividing a tall packed tower into series of small towers is to________________________?

• (A)  Minimise the overall pressure drop
• (B)  Avoid flooding
• (C)  Reduce liquid hold up
• (D)  Avoid channelling

Answer

Submitted By :Ali Uppal