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MCQOPTIONS
This section includes 341 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Process Calculation knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
An adiabatic heat exchanger is used to heat cold water at 15°C entering at a rate of 5 kg/s by hot air at 90°C entering also at rate of 5 kg/s. If the exit temperature of hot air is 20°C, the exit temperature of cold water is |
| A. | 27°C |
| B. | 32°C |
| C. | 52°C |
| D. | 85°C |
| Answer» C. 52°C | |
| 52. |
An after cooler is used to |
| A. | remove impurities from air |
| B. | reduce volume of air |
| C. | cause moisture and oil vapour to drop out |
| D. | cool the air |
| Answer» E. | |
| 53. |
In a counter-flow heat exchanger, cold fluid enters at 30°C and leaves at 50°C, whereas the hot fluid enters at 150°C and leaves at 130°C. The mean temperature difference for this case is |
| A. | 20 °C |
| B. | 80 °C |
| C. | 100 °C |
| D. | 120 °C |
| Answer» D. 120 °C | |
| 54. |
____ is a cooling medium applied for normalizing process. |
| A. | Oil |
| B. | Under sand |
| C. | Air |
| D. | Water |
| Answer» D. Water | |
| 55. |
Air enters in a counter flow heat exchanger at 70°C and leaves at 40°C. Water enters at 30°C and leaves at 50°C The LMTD in °C is |
| A. | 5.65 |
| B. | 14.43 |
| C. | 19.52 |
| D. | 20.17 |
| Answer» C. 19.52 | |
| 56. |
A counter flow shell and tube heat exchanger is used to heat water with hot exhaust gases. The water (C = 4180 J/kg K) flows at the rate of 2 kg/s and the exhaust gases (c = 1000 J/kg K) flow at the rate of 5 kg/s. If the heat transfer surface area is 32 m2 and the overall heat transfer coefficient is 200 Q/m2K, the NTU of the heat exchanger is |
| A. | 4.5 |
| B. | 2.4 |
| C. | 8.6 |
| D. | 1.28 |
| Answer» E. | |
| 57. |
A shell passes and 4 tube passes heat exchanger is used to heat glycerine form 20°C to 50°C by hot water, which enters then thin-walled 2 cm diameter tubes as 80° and leaves at 40°C. The total length of the tubes in the heat exchanger is 60 m. The convection heat transfer coefficient is 25 W/m2°C on the glycerine and 160 W/m2°C on the waterside. Determine, the rate of heat transfer in the heat exchanger before any fouling occurs on the outer surfaces of the tubes, Place [Consider as F = 0.91 (ΔT)LMTD cF = 247°C] |
| A. | 2.65 kW |
| B. | 1.62 kW |
| C. | 1.83 kW |
| D. | 1.81 kW |
| Answer» D. 1.81 kW | |
| 58. |
In a two- fluid heat exchanger, the inlet and outlet temperatures of the hot fluid are 65°C and 40°C respectively. For the cold fluid, these are 15°C and 43°C. The heat exchanger is a |
| A. | Parallel flow heat exchanger |
| B. | Counter flow heat exchanger |
| C. | Mixed flow heat exchanger |
| D. | Phase-change heat exchanger |
| Answer» C. Mixed flow heat exchanger | |
| 59. |
_______ is a process of case hardening in which the outer layer is made hard by increasing amount of carbon. |
| A. | Annealing |
| B. | Normalizing |
| C. | Carburizing |
| D. | Tempering |
| Answer» D. Tempering | |
| 60. |
In a heat exchanger, it is observed that ΔT1 = ΔT2, where ΔT1 is the temperature difference between the two single phase fluid streams at one end and ΔT2 is the temperature difference at the other end. This heat exchanger is |
| A. | a condenser |
| B. | an evaporator |
| C. | a counter flow heat exchanger |
| D. | a parallel flow heat exchanger |
| Answer» D. a parallel flow heat exchanger | |
| 61. |
If the temperature of a hot body is increased by 50%, the amount of radiations emitted by it would increase by nearly |
| A. | 200% |
| B. | 500% |
| C. | 50% |
| D. | 100% |
| Answer» C. 50% | |
| 62. |
A gray body (E = 0.8) emits the same amount of heat as a black body at 1075 K. Find out the required temperature of the gray body |
| A. | 1146.72 K |
| B. | 1136.72 K |
| C. | 1126.72 K |
| D. | 1116.72 K |
| Answer» C. 1126.72 K | |
| 63. |
With an increase in wavelength, the monochromatic emissive power of a black body |
| A. | Increases |
| B. | Decreases |
| C. | Decreases, reaches a minimum and then increases |
| D. | Increases, reaches a maximum and then decreases |
| Answer» E. | |
| 64. |
Interchange factor for infinitely long concentric cylinders is given by |
| A. | 1/ [A₁/A₂ (1/E₂ – 1)]. |
| B. | [1/E₁ + A₁/A₂ (1/E₂ – 1)]. |
| C. | 2/ [1/E₁ + A₁/A₂ (1/E₂ – 1)]. |
| D. | 1/ [1/E₁ + A₁/A₂ (1/E₂ – 1)]. |
| Answer» E. | |
| 65. |
Planck’s law is given by |
| A. | (E) b = 2 π c² h (Wavelength)¯⁵/[c h/k (Wavelength) T] – 2 |
| B. | (E) b = π c² h [exponential [c h/k (Wavelength) T] – 3]. |
| C. | (E) b = 2 π c² h (Wavelength)¯⁵/exponential [c h/k (Wavelength) T] – 1 |
| D. | (E) b = 2 c² h (Wavelength)¯⁵/exponential [c h/k (Wavelength) T] – 6 |
| Answer» D. (E) b = 2 c² h (Wavelength)¯⁵/exponential [c h/k (Wavelength) T] – 6 | |
| 66. |
A blind cylindrical hole of 2 cm diameter and 3 cm length is drilled into a metal slab having emissivity 0.7. If the metal slab is maintained at 650 K, make calculations for the radiation heat escape from the hole |
| A. | 7 W |
| B. | 3 W |
| C. | 1 W |
| D. | 9 W |
| Answer» C. 1 W | |
| 67. |
What is the shape factor of hemispherical surface closed by a plane surface of diameter d? |
| A. | 0 |
| B. | 1.5 |
| C. | 1 |
| D. | 0.5 |
| Answer» E. | |
| 68. |
Which of the following have a continuous spectrum? |
| A. | Solids |
| B. | Liquids |
| C. | Gases |
| D. | Solids and liquids |
| Answer» E. | |
| 69. |
If the emitted radiant energy is to be doubled, to what temperature surface of black body needs to be raised? Take radiant flux density as 11631.7 W/m 2. |
| A. | 894.4 K |
| B. | 200.4 K |
| C. | 800.3 K |
| D. | 600.4 K |
| Answer» E. | |
| 70. |
Which one is having lowest value of fouling factor? |
| A. | Lake river |
| B. | Distilled water |
| C. | Transformers |
| D. | Lubricating oil |
| Answer» C. Transformers | |
| 71. |
What is the value of shape factor for two infinite parallel surfaces separated by a distance x? |
| A. | 0 |
| B. | 1 |
| C. | x |
| D. | Infinity |
| Answer» C. x | |
| 72. |
A small black body has a total emissive power of 4.5 k W/m². In which range of the spectrum does this wavelength fall? |
| A. | Thermal region |
| B. | Cosmic region |
| C. | Visible region |
| D. | Infrared region |
| Answer» E. | |
| 73. |
A 250 mm by 250 mm ingot casting, 1.5 m high and at 1225 K temperature, is stripped from its mold. The casting is made to stand on end on the floor of a large foundry whose wall, floor and roof can be assumed to be at 300 K temperature. Make calculation for the rate of radiant heat interchange between the casting and the room. The casting material has an emissivity of 0.85 |
| A. | 161120 W |
| B. | 171120 W |
| C. | 181120 W |
| D. | 191120 W |
| Answer» C. 181120 W | |
| 74. |
Consider a system of concentric spheres of radius r 1 and r 2 (r 2 is greater than r 1). If r 1 = 5 cm, determine the radius r 2 if it is desired to have the value of shape factor F 21 equal to 0.6 |
| A. | 6.45 cm |
| B. | 7.45 cm |
| C. | 8.45 cm |
| D. | 9.45 cm |
| Answer» B. 7.45 cm | |
| 75. |
The grey body shape factor for radiant heat exchange between a small body (emissivity = 0.4) in a large enclosure (emissivity = 0.5) is |
| A. | 0.1 |
| B. | 0.2 |
| C. | 0.4 |
| D. | 0.5 |
| Answer» D. 0.5 | |
| 76. |
Consider a beam of monochromatic radiation at wavelength λ that enters a layer of absorbing gas. As the beam passes through the gas layer, its intensity |
| A. | Decreases |
| B. | Increases |
| C. | Become twice |
| D. | Remains same |
| Answer» B. Increases | |
| 77. |
The sun emits maximum radiation of 0.52 micron meter. Assuming the sun to be a black body, Calculate the surface temperature of the sun |
| A. | 2345 K |
| B. | 5573 K |
| C. | 9847 K |
| D. | 6492 K |
| Answer» C. 9847 K | |
| 78. |
The sun emits maximum radiation of 0.52 micron meter. Assuming the sun to be a black body, Calculate the emissive ability of the sun’s surface at that temperature |
| A. | 3.47 * 10⁷ W/m² |
| B. | 4.47 * 10⁷ W/m² |
| C. | 5.47 * 10⁷ W/m² |
| D. | 6.47 * 10⁷ W/m² |
| Answer» D. 6.47 * 10⁷ W/m² | |
| 79. |
According to Stefan-Boltzmann law of thermal radiation |
| A. | q = α A T |
| B. | q = α A T⁴ |
| C. | q = α A T³ |
| D. | q = α A T⁵ |
| Answer» C. q = α A T³ | |
| 80. |
Two spheres A and B of same material have radius 1 m and 4 m, and temperatures 4000 K and 2000 K respectively. Then the energy radiated by sphere A is |
| A. | Greater than that of sphere B |
| B. | Less than that of sphere B |
| C. | Equal to that of sphere B |
| D. | Two times that of sphere B |
| Answer» D. Two times that of sphere B | |
| 81. |
What is the wavelength band for solar radiation? |
| A. | 1 * 10¯¹ to 3 micron meter |
| B. | 1 * 10¯¹ to 2 micron meter |
| C. | 1 * 10¯¹ to 1 micron meter |
| D. | 1 * 10¯¹ to 10 micron meter |
| Answer» B. 1 * 10¯¹ to 2 micron meter | |
| 82. |
Two large parallel planes with emissivity 0.4 are maintained at different temperatures and exchange heat only by radiation. What percentage change in net radiative heat transfer would occur if two equally large radiation shields with surface emissivity 0.04 are introduced in parallel to the plates? |
| A. | 65.1% |
| B. | 75.1% |
| C. | 85.1% |
| D. | 95.1% |
| Answer» E. | |
| 83. |
A cavity in the shape of a frustum of a cone has diameter 30 cm and 60 cm and the height is 80 cm. If the cavity is maintained at temperature of 800 K, determine the heat loss from the cavity when the smaller diameter is at the bottom |
| A. | 6577 W |
| B. | 2367 W |
| C. | 8794 W |
| D. | 3675 W |
| Answer» B. 2367 W | |
| 84. |
A thermos flask has a double walled bottle and the space between the walls is evacuated so as to reduce the heat flow. The bottle surfaces are silver plated and the emissivity of each surface is 0.025. If the contents of the bottle are at 375 K, find the rate of heat loss from the thermos bottle to the ambient air at 300 K |
| A. | 5.38 W |
| B. | 6.38 W |
| C. | 7.38 W |
| D. | 8.38 W |
| Answer» E. | |
| 85. |
Two black discs each of diameter 50 cm are placed parallel to each other concentrically at a distance of one meter. The discs are maintained at 1000 K and 500 K. Calculate the heat flow between the discs when no other surface is present |
| A. | 317.27 W |
| B. | 417.27 W |
| C. | 517.27 W |
| D. | 617.27 W |
| Answer» C. 517.27 W | |
| 86. |
Amount of heat energy radiated by unit surface of the sun in the same time workout asTake, R = mean distance of earth from the sun and r = radius of sun |
| A. | E = π R² S/4 π R² |
| B. | E = 4 π R² S/4 π R² |
| C. | E = 4 π R² |
| D. | E = 4 π R² S |
| Answer» C. E = 4 π R² | |
| 87. |
A metal sphere of surface area 0.0225 m² is in an evacuated enclosure whose walls are held at a very low temperature. Electric current is passed through resistors imbedded in the sphere causing electrical energy to be dissipated at the rate of 75 W. If the sphere surfaces temperature is measured to be 560 K, while in steady state, calculate emissivity of the sphere surface |
| A. | 0.498 |
| B. | 0.598 |
| C. | 0.698 |
| D. | 0.798 |
| Answer» C. 0.698 | |
| 88. |
Which one is having lowest value of solar absorptivity? |
| A. | Snow |
| B. | Red brick |
| C. | Aluminum foil |
| D. | Polished aluminum |
| Answer» E. | |
| 89. |
A thermos flask has a double walled bottle and the space between the walls is evacuated so as to reduce the heat flow. The bottle surfaces are silver plated and the emissivity of each surface is 0.025. If the contents of the bottle are at 375 K and temperature of ambient air is 300 K. What thickness of cork (k = 0.03 W/m degree) would be required if the same insulating effect is to be achieved by the use of cork? |
| A. | 26.8 cm |
| B. | 25.8 cm |
| C. | 24.8 cm |
| D. | 23.8 cm |
| Answer» B. 25.8 cm | |
| 90. |
The heat energy absorbed by a known area in a fixed time is determined with the help of an instrument called |
| A. | Psychrometer |
| B. | Pyrheliometer |
| C. | Thermometric well |
| D. | Any instrument |
| Answer» C. Thermometric well | |
| 91. |
The value of radiation coefficient or the Stefan-Boltzmann constant is |
| A. | 5.67 * 10¯⁸ W/m² K⁴ |
| B. | 5.67 * 10¯⁷ W/m² K⁴ |
| C. | 5.67 * 10¯⁶ W/m² K⁴ |
| D. | 5.67 * 10¯⁵ W/m² K⁴ |
| Answer» B. 5.67 * 10¯⁷ W/m² K⁴ | |
| 92. |
The value of shape factor depends on how many factors? |
| A. | 4 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» D. 3 | |
| 93. |
If I n denotes the normal intensity and I α represents the intensity at angle α, then |
| A. | I α = 2 I n cos α |
| B. | I α = 3 I n cos α |
| C. | I α = 4 I n cos α |
| D. | I α = I n cos α |
| Answer» E. | |
| 94. |
What is the value of solar absorptivity for polished stainless steel? |
| A. | 0.37 |
| B. | 0.36 |
| C. | 0.35 |
| D. | 0.34 |
| Answer» B. 0.36 | |
| 95. |
A furnace having inside temperature of 2250 has a glass circular viewing of 6 cm diameter. If the transmissivity of glass is 0.08, make calculations for the heat loss from the glass window due to radiation |
| A. | 234.54 W |
| B. | 652.32 W |
| C. | 328.53 W |
| D. | 762.32 W |
| Answer» D. 762.32 W | |
| 96. |
The total radiant energy incident upon a surface per unit time per unit area is known as |
| A. | Shape factor |
| B. | Radiosity |
| C. | Radiation |
| D. | Irradiation |
| Answer» E. | |
| 97. |
Which one is having highest value of solar absorptivity? |
| A. | White marble |
| B. | Concrete |
| C. | Asphalt |
| D. | Snow |
| Answer» D. Snow | |
| 98. |
For the same type of shapes, the value of radiation shape factor will be higher when |
| A. | Surfaces are closer |
| B. | Surfaces are larger and held closer |
| C. | Surfaces are moved further apart |
| D. | Surfaces are smaller and held closer |
| Answer» C. Surfaces are moved further apart | |
| 99. |
A black body of 0.2 m² area has an effective temperature of 800 K. Calculate the intensity of normal radiations |
| A. | 1234.65 W/m² sr |
| B. | 7396.28 W/m² sr |
| C. | 3476.74 W/m² sr |
| D. | 8739.43 W/m² sr |
| Answer» C. 3476.74 W/m² sr | |
| 100. |
What is the value of solar absorptivity for snow? |
| A. | 0.25 |
| B. | 0.26 |
| C. | 0.27 |
| D. | 0.28 |
| Answer» E. | |