Practice Pakistan's most useful MCQs for competitive exams

Desirable value of absorption factor in an absorber is___________________?

• (A)  1
• (B)  < 1
• (C)  > 1
• (D)  0.5

Answer

Submitted By :Ali Uppal

Leaching of coffee from coffee beans is done by___________________?

• (A)  Hot water
• (B)  Hexane
• (C)  Lime water
• (D)  Dilute H2SO4 (hot)

Answer

Submitted By :Ali Uppal

If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that___________________?

• (A)  The system comprises of partially miscible liquids
• (B)  The system comprises of miscible liquids
• (C)  The system comprises of an azeotrope
• (D)  On heating, a vapor phase will appear; while on cooling, a solid phase will appear

Answer

Submitted By :Ali Uppal

With increase in solvent rate, the number of transfer units, NtoG, for a fixed degree of absorption from a fixed amount of gas________________?

• (A)  Increases
• (B)  Decreases
• (C)  Decreases linearly
• (D)  Remain unaffected

Answer

Submitted By :Ali Uppal

The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the ______________ temperature?

• (A)  Dew point
• (B)  Wet bulb
• (C)  Dry bulb
• (D)  None of these

Answer

Submitted By :Ali Uppal

The adiabatic saturation curve for a vapour-gas mixture is__________________?

• (A)  Straight line
• (B)  Slightly concave upward
• (C)  Slightly concave downward
• (D)  None of these

Answer

Submitted By :Ali Uppal

Flights in a rotary dryer are provided to________________?

• (A)  Lift and shower the solids thus exposing it thoroughly to the drying action of the gas
• (B)  Reduce the residence time of solid
• (C)  Increase the residence time of the solid
• (D)  None of these

Answer

Submitted By :Ali Uppal

Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the_________________?

• (A)  Relative volatility is reasonably constant
• (B)  Mixture (to be separated) shows negative deviation from ideality
• (C)  Mixture (to be separated) shows positive deviation from ideality
• (D)  Multi-component distillation is involved

Answer

Submitted By :Ali Uppal

Use of raschig rings in place of crushed stones as packing in packed beds (other things being same) ?

• (A)  Increases pressure drop, increases surface area
• (B)  Increases pressure drop, decreases surface area
• (C)  Decreases pressure drop, increases surface area
• (D)  Decreases pressure drop, decreases surface area

Answer

Submitted By :Ali Uppal

The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by___________________?

• (A)  Increasing the gas film co-efficient
• (B)  Increasing the liquid film co-efficient
• (C)  Increasing the total pressure
• (D)  Decreasing the total pressure

Answer

Submitted By :Ali Uppal