Practice Pakistan's most useful MCQs for competitive exams

Duhring‟s rule is important in solving problems on__________________?

• (A)  Distillation
• (B)  Crystallisation
• (C)  Evaporation
• (D)  Humidification

Answer

Submitted By :Ali Uppal

Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperature of Ta°C depends on_____________?

• (A)  T1 – T2
• (B)  T1 – Ta
• (C)  T2 – Ta
• (D)  None of these

Answer

Submitted By :Ali Uppal

The film thickness for laminar film condensation on vertical surface _____________ from top to bottom?

• (A)  Cumulatively increases
• (B)  Cumulatively decreases
• (C)  Remain constant
• (D)  And the surface conductance increase

Answer

Submitted By :Ali Uppal

Pick out the wrong statement?

• (A)  The capacity of an evaporator is reduced by the boiling point elevation
• (B)  Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger
• (C)  Steam jet ejector is used for vapor compression in a thermal recompression evaporator
• (D)  Heat sensitive materials should be concentrated in high pressure evaporators

Answer

Submitted By :Ali Uppal

For evaporation of viscous solution in a multiple effect evaporator, the preferred feeding scheme is _________________?

• (A)  Forward
• (B)  Backward
• (C)  Parallel
• (D)  None of these

Answer

Submitted By :Ali Uppal

1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the liquid is 1500 W/m2.°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be__________________?

• (A)  15 min
• (B)  22 min
• (C)  44 min
• (D)  51 min

Answer

Submitted By :Ali Uppal

Heat waves_____________________?

• (A)  Cannot pass through vacuum
• (B)  Travel in straight line
• (C)  Can be reflected by a mirror
• (D)  Both

Answer

Submitted By :Ali Uppal

If air (a non-condensing gas) is present in a condensing vapor stream, it will ______________ the condensation rate of vapor?

• (A)  Increase
• (B)  Decrease
• (C)  Not affect
• (D)  Increase the condensing film co-efficient as well as

Answer

Submitted By :Ali Uppal

For a perfectly transparent surface (like gases), the____________________?

• (A)  Absorptivity = 0
• (B)  Transmissivity = 1
• (C)  Reflectivity = 0
• (D)  All

Answer

Submitted By :Ali Uppal

A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to_____________________?

• (A)  d0.8
• (B)  d-0.2
• (C)  d-1
• (D)  d-1.8

Answer

Submitted By :Ali Uppal