Practice Pakistan's most useful MCQs for competitive exams

As the reflux ratio decreases, the_________________?

• (A)  Separation becomes more efficient
• (B)  Number of plates increases
• (C)  Column diameter increases
• (D)  None of these

Answer

Submitted By :Ali Uppal

With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature) ?

• (A)  Increases
• (B)  Remains unchanged
• (C)  Decreases
• (D)  Decreases linearly

Answer

Submitted By :Ali Uppal

Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter) ?

• (A)  0.5 D
• (B)  D
• (C)  1.5 D
• (D)  2 D

Answer

Submitted By :Ali Uppal

Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is ______________ microns?

• (A)  < 5
• (B)  10 to 25
• (C)  < 74
• (D)  > 1000

Answer

Submitted By :Ali Uppal

Which of the following mechanical conveyors does not come under the division „carriers‟ ?

• (A)  Belt conveyor
• (B)  Bucket elevator
• (C)  Screw conveyor
• (D)  Apron conveyor

Answer

Submitted By :Ali Uppal

Which of the following is not used as filter aid ?

• (A)  Asbestos
• (B)  Diatomaceous earth
• (C)  Purified wood cellulose
• (D)  Rice husk

Answer

Submitted By :Ali Uppal

_____________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid ?

• (A)  Dew point
• (B)  Bubble point
• (C)  Dry bulb temperature
• (D)  Wet bulb temperature

Answer

Submitted By :Ali Uppal

For absorbers, high pressure drop results in___________________?

• (A)  Increased efficiency
• (B)  Decreased efficiency
• (C)  High operating cost
• (D)  Better gas liquid contact

Answer

Submitted By :Ali Uppal

The binary diffusivity in gases at atmospheric conditions is about ___________________?

• (A)  10-9 cm/sec
• (B)  10-1 cm2/sec
• (C)  10-3 sec/cm
• (D)  10-4 cm2/sec2

Answer

Submitted By :Ali Uppal

Occurrence of ‘case hardening’ during drying of a high moisture solid cake _______________ the drying rate?

• (A)  Increases
• (B)  Decreases
• (C)  Does not affect
• (D)  Exponentially increases

Answer

Submitted By :Ali Uppal