MCQOPTIONS
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MCQOPTIONS
This section includes 425 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
While the total emissivity of a perfect black body is unity, the same for a real body is__________________? |
| A. | 0 |
| B. | 1 |
| C. | > 1 |
| D. | Between 0 and 1 |
| Answer» E. | |
| 2. |
With increase in porosity, the thermal conductivity of a solid substance__________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on the solid |
| Answer» C. Remains unchanged | |
| 3. |
With increase in temperature, the thermal conductivity of fresh lubricating oil ___________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on its composition |
| Answer» C. Remains unchanged | |
| 4. |
With increase in temperature, the thermal conductivity of most liquids_________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | First increases upto a certain temperature and then becomes constant |
| Answer» C. Remain same | |
| 5. |
With increase in temperature, the thermal conductivity of a gas ___________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | May increase or decrease depending on the type of gas |
| Answer» B. Decreases | |
| 6. |
With increase in temperature, the thermal conductivity of non-metallic amorphous solids_________________? |
| A. | Decreases |
| B. | Increases |
| C. | Remain constant |
| D. | First decreases upto certain temperature and then increases |
| Answer» C. Remain constant | |
| 7. |
With increase in temperature, the total emissivity of conductors____________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remain same |
| D. | Decreases linearly |
| Answer» B. Decreases | |
| 8. |
With increase in temperature, the thermal conductivity of steel___________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» C. Remains unchanged | |
| 9. |
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer ? |
| A. | Decreases |
| B. | Increases |
| C. | Increases exponentially |
| D. | Remain unaffected |
| Answer» B. Increases | |
| 10. |
With the increase of temperature, the Col-burn jH factor_____________________? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depending on temperature |
| Answer» B. Decreases | |
| 11. |
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger ? |
| A. | Corrosiveness & fouling characteristics |
| B. | Pressure |
| C. | Viscosity |
| D. | Density |
| Answer» E. | |
| 12. |
Which of the following is not concerned with the heat transfer ? |
| A. | Brinkman number |
| B. | Stanton number |
| C. | Schmidt number |
| D. | Peclet number |
| Answer» D. Peclet number | |
| 13. |
Which of the following is generally considered as opaque surface towards radiations ? |
| A. | Gases |
| B. | Solids |
| C. | Liquids |
| D. | Both B. and C. |
| Answer» E. | |
| 14. |
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» B. Long tube vertical evaporator | |
| 15. |
When warm and cold liquids are mixed, the heat transfer is mainly by_______________? |
| A. | Conduction |
| B. | Convection |
| C. | Radiation |
| D. | Both A. & C. |
| Answer» C. Radiation | |
| 16. |
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as ___________________ boiling? |
| A. | Pool |
| B. | Nucleate |
| C. | Transition |
| D. | Film |
| Answer» E. | |
| 17. |
When vaporisation takes place directly at the heating surface, it is called________________? |
| A. | Film boiling |
| B. | Nucleate boiling |
| C. | Vapour binding |
| D. | None of these |
| Answer» C. Vapour binding | |
| 18. |
When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is _______________? |
| A. | Free convection |
| B. | Entry length problem in laminar forced conduction (developing thermal boundary layer) |
| C. | Mixed convection (both free and forced) |
| D. | Forced convection |
| Answer» D. Forced convection | |
| 19. |
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is ________________ law? |
| A. | Stefan’s |
| B. | Dalton’s |
| C. | Wien’s |
| D. | Kirchoff’s |
| Answer» D. Kirchoff’s | |
| 20. |
Water is normally used as a coolant in the heat exchange equipments mainly because of its___________________? |
| A. | Abundance & high heat capacity |
| B. | Low density |
| C. | Low viscosity |
| D. | High fluidity |
| Answer» B. Low density | |
| 21. |
Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ? |
| A. | 35.5 |
| B. | 43.75 |
| C. | 81.25 |
| D. | 48.25 |
| Answer» D. 48.25 | |
| 22. |
Viscous & heat sensitive liquids are concentrated in _____________ evaporators? |
| A. | Open pan |
| B. | Long tube |
| C. | Agitated film |
| D. | None of these |
| Answer» D. None of these | |
| 23. |
Viscosity of gases ______________ with increase in temperature? |
| A. | Increase very rapidly |
| B. | Increase slowly |
| C. | Decrease slowly |
| D. | Remain unaffected |
| Answer» C. Decrease slowly | |
| 24. |
View factor is important in heat transfer by_____________________? |
| A. | Steady state conduction |
| B. | Natural convection |
| C. | Forced convection |
| D. | Radiation |
| Answer» E. | |
| 25. |
Vibrations in the tubes of a shell and tube heat exchanger is induced due to the _________________? |
| A. | Flow of fluid on the tube and shell sides |
| B. | Oscillations in the flow of shell/tube sides fluid |
| C. | Vibrations transmitted through piping and/or supports due to external reasons |
| D. | All A., B. and C. |
| Answer» E. | |
| 26. |
Vent pipes are provided in a condenser to ________________? |
| A. | Remove non-condensable gases |
| B. | Purge the condenser |
| C. | Facilitate easy cleaning of tubes |
| D. | None of these |
| Answer» B. Purge the condenser | |
| 27. |
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» C. 100 to 500 | |
| 28. |
Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is__________________? |
| A. | 0.5 |
| B. | 2 |
| C. | 10 |
| D. | 100 |
| Answer» C. 10 | |
| 29. |
Vacuum is generally maintained in the vapour space of an evaporator mainly to__________________? |
| A. | Get economical temperature difference by using moderate pressure steam |
| B. | Facilitate forward feeding in multiple effect evaporation |
| C. | Concentrate heat sensitive materials |
| D. | Achieve very high concentration of the final product |
| Answer» B. Facilitate forward feeding in multiple effect evaporation | |
| 30. |
Use of transverse baffles in a shell and tube heat exchanger is done to increase the___________________? |
| A. | Rate of heat transfer |
| B. | Flow velocity |
| C. | Turbulence of shell side fluid |
| D. | All A., B. and C. |
| Answer» E. | |
| 31. |
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» C. Heat flows in one direction only | |
| 32. |
Tubes are held between top and bottom tube sheets in Calandria type evaporator by keeping_________________? |
| A. | Both the tube sheets fixed |
| B. | Both the tube sheets floating |
| C. | The top tube sheet floating and bottom tube sheet fixed |
| D. | The top tube sheet fixed and the bottom tube-sheet floating |
| Answer» B. Both the tube sheets floating | |
| 33. |
Tube pitch is the _______________ of tube diameters and the clearances? |
| A. | Sum |
| B. | Difference |
| C. | Ratio |
| D. | None of these |
| Answer» B. Difference | |
| 34. |
Tube expansion allowances exist in _____________ heat exchanger? |
| A. | Multipass fixed tube sheet |
| B. | U-tube |
| C. | Single pass fixed tube sheet |
| D. | None of these |
| Answer» C. Single pass fixed tube sheet | |
| 35. |
Trap is used to remove ________________ from steam pipe lines? |
| A. | Steam |
| B. | Condensate |
| C. | Non-condensable |
| D. | None of these |
| Answer» C. Non-condensable | |
| 36. |
To reduce the tube side pressure drop for the same flow rate, the heat exchanger recommended is _______________? |
| A. | 1-2 heat exchanger |
| B. | 1-1 heat exchanger |
| C. | 3-2 heat exchanger |
| D. | 2-4 heat exchanger |
| Answer» C. 3-2 heat exchanger | |
| 37. |
Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C? |
| A. | 40 |
| B. | 95 |
| C. | 70 |
| D. | 50 |
| Answer» D. 50 | |
| 38. |
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is_________________? |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | > 5 |
| Answer» C. > 1 | |
| 39. |
Thermal diffusivity of a material __________________? |
| A. | Has the unit m2 /sec |
| B. | Is defined as K/ρ . Cp |
| C. | Is the ratio of thermal conductivity to thermal capacity |
| D. | All A., B. and C. |
| Answer» E. | |
| 40. |
Thermal diffusivity is the most important in heat transfer by__________________? |
| A. | Conduction |
| B. | Radiation |
| C. | Condensation |
| D. | Natural convection |
| Answer» B. Radiation | |
| 41. |
Thermal diffusivity is given by__________________? |
| A. | k/ρCp |
| B. | ρCp/k |
| C. | μCp/a |
| D. | μ/hCp |
| Answer» B. ρCp/k | |
| 42. |
Thermal conductivity of a conducting solid material depends upon its_______________? |
| A. | Temperature |
| B. | Porosity |
| C. | Both A. & B. |
| D. | Neither A. nor B. |
| Answer» D. Neither A. nor B. | |
| 43. |
Thermal conductivity of a gas at low density, ___________ with increase in temperature ? |
| A. | Decreases |
| B. | Increases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on the gas |
| Answer» C. Remains unchanged | |
| 44. |
Thermal conductivities of most of the liquids _______________ with rise in temperature? |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | May increase or decrease; depends on the liquid |
| Answer» C. Remains unchanged | |
| 45. |
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)? |
| A. | αT |
| B. | α × 1/T |
| C. | α T4 |
| D. | Independent of T |
| Answer» C. α T4 | |
| 46. |
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of ‘a’ in SI system will be________________? |
| A. | W/m.k |
| B. | W/m |
| C. | W/m.k2 |
| D. | None, ‘a’ is just a number |
| Answer» D. None, ‘a’ is just a number | |
| 47. |
The value of Stefan-Boltzmann constant in SI unit is_________________? |
| A. | 5.6697 × 10-8W/m2.°K4 |
| B. | 0.1714 × 10-8W/m2.°K4 |
| C. | 5.6697 × 10-8kcal/m2. °K4 |
| D. | 0.1714 × 10-8kcal/m2. °K4 |
| Answer» B. 0.1714 × 10-8W/m2.°K4 | |
| 48. |
The units of resistance to heat transfer is _____________________? |
| A. | J.m-2.K-1 |
| B. | J.m-1.K-1 |
| C. | W.m-2.K-1 |
| D. | W-1m2K |
| Answer» E. | |
| 49. |
The unit of heat transfer co-efficient is_________________? |
| A. | BTU/hr. ft2°F |
| B. | BTU/hr. °F. ft |
| C. | BTU/hr. °F |
| D. | BTU/hr. ft |
| Answer» B. BTU/hr. °F. ft | |
| 50. |
The unit of heat transfer co-efficient in SI unit is____________________? |
| A. | J/M2°K |
| B. | W/m2°K |
| C. | W/m°K |
| D. | J/m°K |
| Answer» C. W/m°K | |