Practice Pakistan's most useful MCQs for competitive exams

Height equivalent to a theoretical plate (HETP) is the height of packing that will give the same separation as one theoretical plate in gas-liquid mass transfer operations like distillation, absorption/stripping and humidification/dehumidification. HETP which is experimentally determined, depends upon the_______________?

• (A)  Flow rates of each fluid
• (B)  Type and size of packing
• (C)  Concentration of each fluid
• (D)  All A,

Answer

Submitted By :Ali Uppal

Heat transfer co-efficient, hG(Kcal/hr.m2 .°C) and mass velocity of air, G (kg/hr.m2 ) for air flow parallel to the surface in case of constant drying rate in batch drying is related as hG = 0.0176G0.8. But when the flow of air perpendicular to the surface is encountered, this equation changes to ____________________?

• (A)  hG = 1.004G0.37
• (B)  1.004G0.8
• (C)  hG = 0.0176G0.37
• (D)  0.0176G1.37

Answer

Submitted By :Ali Uppal

The most common standard size of bubble caps used in industrial operation is___________________?

• (A)  1″ dia cap with 0.5″ dia riser
• (B)  6″ dia cap with 4″ dia riser
• (C)  8″ dia cap with 1″ dia riser
• (D)  4″ dia cap with 8″ dia riser

Answer

Submitted By :Ali Uppal

Minimum baffle spacing recommended in a shell and tube heat exchanger is equal to _____________________?

• (A)  5 cms
• (B)  40% of the I.D. of the shell
• (C)  25 cms
• (D)  I.

Answer

Submitted By :Ali Uppal

For identical situation, condensing film coefficient in case of a horizontal condenser is almost ______________ the value expected in case of vertical condenser?

• (A)  Half
• (B)  Twice
• (C)  Thrice
• (D)  Five times

Answer

Submitted By :Ali Uppal

Length to diameter ratio of most rotary driers is in the range of____________________?

• (A)  1 to 2
• (B)  4 to 10
• (C)  10 to 20
• (D)  20 to 30

Answer

Submitted By :Ali Uppal

Apex angle of conical heads used in the bottom heads of chemical process equipments is usually__________________?

• (A)  30°
• (B)  45°
• (C)  60°
• (D)  75°

Answer

Submitted By :Ali Uppal

With increase in pressure drop (for a given particle size), the dust collection efficiency of a cyclone separator will________________?

• (A)  Increase
• (B)  Decrease
• (C)  Remain unaffected
• (D)  Increase or decrease depending on the nature of the dust

Answer

Submitted By :Ali Uppal

“A claming section” before the liquid flows into the downcomer is provided to__________________?

• (A)  Permit release of entrained vapour in the liquid
• (B)  Reduce the discharge fluctuation
• (C)  Ensure better vapour-liquid contact
• (D)  Cool the liquid before it flows down

Answer

Submitted By :Ali Uppal

In sieve plate column, holes are drilled or punched in sizes ranging from 2.5 to 12 mm (5 mm being widely used). The hole pitch is normally ______________ times the hole diameter to give the required hole area?

• (A)  0.5 to 1.5
• (B)  2.5 to 4.0
• (C)  5 to 10
• (D)  10 to 15

Answer

Submitted By :Ali Uppal