1. Which of the following material has highest value of thermal diffusivity?
Correct : C. Lead
2. The quantity of heat required to change the temperature of 1 gm of ice from -6?C to -5?C is known as
Correct : D. Specific heat
3. For temperature below -40?C which one of the following substance can be used as thermometric substance
Correct : D. Any of the above
4. The conditions under which three phases of matter can coexist in equilibrium, is known as
Correct : B. Triple point
5. The process of removal of oil from oil cakes is known as
Correct : A. Leaching
6. A thermistor is a
Correct : A. Miniature resistance
7. In the electrical network analysis method the total radiation which leaves a surface per unit time per unit area is termed as
Correct : E. Radiosity
8. If in a system ratios of the velocity and acceleration of the homologous particles are equal, the similarity being considered is
Correct : B. kinematic similarity
9. A wet solid is to be dried from 80% to 50% moisture (on wet basis). Calculate the moisture to be evaporated for 10 tonns of dried product?
Correct : B. 37,500 kg
10. Grashoff number has significant role in heat transfer by
Correct : C. natural connection
11. Least value of Prandlt number can be expected in case of
Correct : E. Liquid metals
12. Heat conduction does not occur
Correct : C. If the temperature difference between the bodies does not exist
13. The triple point temperature for water is
Correct : C. 0.01?C
14. The numerical value of which property of air generally drops with rising temperature
Correct : B. Density
15. For all substances the absorptivity must lie between
Correct : E. 0 and 1
16. A black body absorbs all radiations. As a result of absorption of these radiations
Correct : B. The temperature of black body rises
17. Thermal diffusivity is least for
Correct : B. Rubber
18. A block of wood and a block of metal feel equally cold or equally hot when touched. Then their common temperature is
Correct : E. the same as that of the human body
19. The expression (A2-A1)/loge (A2/A1) for a hollow cylinder is known as
Correct : B. Mean area of heat transfer
20. "The boiling point of a solution is a linear function of water at the same pressure". The above statement is associated with
Correct : A. Dubring's rule
21. When a vapour condenses into a liquid
Correct : B. It evolves heat
22. If the absorptivity plus reflectivity of a body equals 1, then the body is known as
Correct : C. Opaque body
23. Prandtl number for liquid metals is generally in the range
Correct : B. 0.003 to 0.01
24. A sphere of radius 40 cm is lagged to a radius of 50 cm. The temperatures of outer and inner surfaces are 66?C and 235?C respectively. Thermal conductivity of logging per cm thickness is 0.7 kcal/m-hr?C. The rate of heat leakage will be
Correct : D. 298 kcal/hr
25. A non-dimensional number generally associated with natural convection heat transfer is
Correct : E. Grashof number
26. The first stage of crystal formation is
Correct : A. Nucleation
27. All heat transfer processes
Correct : B. Involve temperature difference between the bodies
28. A Foreman of an automobile workshop wants to measure the temperature inside the piston of a car, whose temperature will be of the order of 700?C (accurate upto 1?C). The best thermometer to use is
Correct : B. Thermo electric thermometer
29. When analogy is drawn between heat flow and electricity flow in circuits, the heat flow of thermal circuits is equated in the electrical circuit against
Correct : D. Current
30. The ratio of the actual vapour pressure to the pressure of saturated vapour at the prevailing dry bulb temperature is known as
Correct : B. Relative humidity
31. A liquid to liquid counterflow heat exchanger is used to heat cold fluid from 50?C to 150?C. Assuming that the hot fluid enters at 250?C and leaves at 200?C, the log mean temperature difference for the heat exchanger will be closer to
Correct : C. 128?C
32. A liquid is boiling in a a air tight vessel. Using an exhaust tube, the vapour is pumped out at a faster rate. What happens to the liquid?
Correct : A. Temperature goes down, doiling continues
33. The surface which diffusely reflects and emits the same amount of energy which it receives by radiation is known as
Correct : D. A perfect radiating surface
34. Which of the following have the same units?
Correct : C. Planck's constant and angular momentum
35. In case of solids, the heat transfer takes place according to
Correct : B. conduction
36. Absolute zero is
Correct : A. 0?C
37. The heat of sum reaches to us according to
Correct : A. radiation
38. A prototype is
Correct : E. a full size structure employed in actual engineering design
39. The equation E = ? AT4 represents
Correct : C. Stefan Boltzmann's law
40. Two pieces of wood are placed in sunlight. One is painted white and the other is painted black. It can be concluded that
Correct : E. Black painted wood will absorb more hcat as compared to white painted wood
41. A dimensionless group which represents the rate of the (product of intertial forces times buoyant forces) to viscous force squared is known as
Correct : D. Grashof number
42. The ratio of heat transfer coefficient to the flow of heat per unit temperature rise due to the velocity of the fluid is known as
Correct : A. Stanton number
43. Which evaporator is preferred for concentrating the fruit juice?
Correct : B. Falling film evaporator
44. A perfect black body is the one which
Correct : A. Absorbs all incident radiation
45. Three rods one made of glass, one of pure aluminium and one made of wrought iron are heated to 150?C. All the rods are 15 mm in diameter and 300 mm long. The lowest temperature at the free end of the rods will occur in case of
Correct : A. Glass rod
46. Non-dimensional number generally involved in case of heat transfer from horizontal cylinder by natural convection is
Correct : E. (B), (C) and (D) above
47. Body A is kept in contact with body B. Heat will flow from A to B, if
Correct : B. The temperature of A is greter than that of B
48. Thermal conductivity of air at room temperature is approximately
Correct : A. 0.02 kcal/m-hr-?C
49. What energy transformation takes place when ice is converted into water
Correct : C. Heat energy to latent heat
50. Which dimensionless number correlates the relative thickness of the hydrodynamic and thermal boundary layers?
Correct : C. Prandlt number
51. Prandtl number for gases is
Correct : C. near unity
52. Molecular transmission of heat is smallest in case of
Correct : D. Gases
53. Which one of the following will have least value of thermal conductivity?
Correct : D. Air
54. Which of the following property of air does not increase with rise in temperature?
Correct : B. Specific gravity
55. Entrainment separator is used in evaporators to
Correct : C. Separate liquid droplets from vapour
56. Which of the following can be used to measure a temperature around -50?C?
Correct : C. Alcohol thermometer
57. The surface temperature of the sun is
Correct : A. 20000?K
58. What whould be shape of an ideal thermometer?
Correct : A. Spherical
59. Fouling factor
Correct : E. Is virtually a factor of safety in heat exchanger design
60. A dimensionless number representing the ratio of inertia forces to viscous forces is known as
Correct : C. Reynolds number
61. Insulation in cavity walls is
Correct : B. Air
62. Thermal conductivity of wood least depends on
Correct : D. Grain orientation
63. Heat is transferred from an insulated pipe to the surrounding still air mainly by
Correct : A. Free convection
64. Dynamic similarity refers to the similarity of
Correct : E. physical dimensions
65. A sphere 15 cm in diameter is covered with 5 cm of insulation (k = 0.057 kcal/m-hr-?C). The inside and outside surface temperature of the insulation are 315?C and 80?C respectively. The heat loss per sq. m of the outside surface will be closer to
Correct : C. 160 kcal/hr
66. The net radiant interchange per square metre for two large parallel planes at temperatures of 1000?K and 100?K respectively, would be roughly
Correct : C. 25 kcal/hr
67. Which variety of steel may be expected to have lowest value of thermal conductivity?
Correct : E. Chromium nickel steel (9% Ni, 18% Cr)
68. In an air-conditioning plant a cooling tower is used to cool
Correct : C. condenser water
69. Which method can be used for heating wood?
Correct : C. Dielectric heating
70. A correction of LMTD is necessary in case of
Correct : C. Cross flow heat exchanger
71. The dimensions of thermal conductivity are
Correct : A. MLT-3 ?-1
72. In which of the following heat exchange process, the value of overall heat transfer coefficient will be highest?
Correct : D. Steam condensers
73. A grey body has emissivity
Correct : C. less than 1
74. The density of water is maximum at
Correct : D. 4?C
75. A thin circulr disc has a concentric hole in it. On heating the diameter of hole will
Correct : D. increase
76. Which is the unit of Stefan Boltzmann constant