Practice Pakistan's most useful MCQs for competitive exams

_____________ equation relates the thermal conductivity of a solid to its temperature ?

• (A)  Antoine
• (B)  Kopp’s
• (C)  Lee’s
• (D)  Kistyakowsky

Answer

Submitted By :Ali Uppal

Unsteady state heat conduction occurs, when_______________?

• (A)  Temperature distribution is independent of time
• (B)  Temperature distribution is dependent on time
• (C)  Heat flows in one direction only
• (D)  Three dimensional heat flow is concerned

Answer

Submitted By :Ali Uppal

For specified tube outside diameter, higher BWG means higher___________________?

• (A)  Tube thickness
• (B)  Cross-sectional area
• (C)  Weight per unit length
• (D)  None of these

Answer

Submitted By :Ali Uppal

A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time ___________________?

• (A)  t = 283 s
• (B)  t = 356 s
• (C)  t = 400 s
• (D)  t = 800 s

Answer

Submitted By :Ali Uppal

Value of Prandtl number for water ranges from_________________?

• (A)  1 to 2
• (B)  5 to 10
• (C)  100 to 500
• (D)  1000 to 2000

Answer

Submitted By :Ali Uppal

For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are__________________?

• (A)  Same
• (B)  Different
• (C)  Never different
• (D)  Linearly related

Answer

Submitted By :Ali Uppal

1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is__________________?

• (A)  520
• (B)  200
• (C)  400
• (D)  500

Answer

Submitted By :Ali Uppal

Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by____________________?

• (A)  Keeping the heat transfer surface clean
• (B)  Enhancing the fluid pumping rate
• (C)  Increasing the tube length
• (D)  None of these

Answer

Submitted By :Ali Uppal

Which is the most suitable for the concert-ration of highly concentrated solution ?

• (A)  Open pan evaporation
• (B)  Long tube vertical evaporator
• (C)  Agitated film evaporator
• (D)  None of these

Answer

Submitted By :Ali Uppal

A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an___________________?

• (A)  Ellipse
• (B)  Straight line
• (C)  Parabola
• (D)  Circular arc

Answer

Submitted By :Ali Uppal