MCQOPTIONS
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MCQOPTIONS
This section includes 968 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The heat transfer co-efficient in film type condensation is __________ that for dropwisecondensation. |
| A. | Greater than |
| B. | Lower than |
| C. | Is same as |
| D. | Half |
| Answer» C. Is same as | |
| 102. |
What is Nusselt number? |
| A. | CP. µ/k |
| B. | hD/k |
| C. | h. CP/µ |
| D. | CP. µ/h |
| Answer» C. h. CP/µ | |
| 103. |
When heat is transferred from one particle of hot body to another by actualmotion of the heated particles, it is referred to as heat transfer by |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | conduction and convection |
| E. | convection and radiation. |
| Answer» B. convection | |
| 104. |
The Dittus-Boelter equation for convective heat transfer [(i.e. h = 0.023 (K/D) (Re) 0.8 (Pr) 0.4] cannot be used for |
| A. | Low Reynold's number |
| B. | Very low Grashoff number |
| C. | Molten metals |
| D. | All (A), (B) and (C) |
| Answer» E. | |
| 105. |
Extremely large or small volumes of fluids are generally best routed through the shell sideof a shell and tube heat exchanger, because of the |
| A. | Less corrosion problems |
| B. | Flexibility possible in the baffle arrangement |
| C. | Low pressure drop |
| D. | High heat transfer co-efficient |
| Answer» C. Low pressure drop | |
| 106. |
In case of surface condensers, a straight line is obtained on plotting 1/U vs. __________ onan ordinary graph paper. |
| A. | 1/V̅-0.8 |
| B. | V̅-0.8 |
| C. | V̅-2 |
| D. | 1/ V̅-2 |
| Answer» B. V̅-0.8 | |
| 107. |
The dimensionless group in mass transfer that is equivalent to Prandtl number in heattransfer is |
| A. | Nusselt number |
| B. | Sherwood number |
| C. | Schmidt number |
| D. | Stanton number |
| Answer» D. Stanton number | |
| 108. |
Duhring‟s rule is important in solving problems on |
| A. | Distillation |
| B. | Crystallisation |
| C. | Evaporation |
| D. | Humidification |
| Answer» D. Humidification | |
| 109. |
Stefan's block body radiation law can also be derived from __________ law. |
| A. | Kirchoff’s |
| B. | Planck's |
| C. | Fourier's |
| D. | None of these |
| Answer» C. Fourier's | |
| 110. |
The heat flux in the nucleate boiling regimes is proportional to (where, ΔT = excesstemperature) |
| A. | (ΔT)2 |
| B. | (ΔT)4 |
| C. | (ΔT)3 |
| D. | √(ΔT) |
| Answer» D. √(ΔT) | |
| 111. |
Choose the most important factor on which the heat conducted through a wall in a unittime will depend on? |
| A. | Thickness of the wall |
| B. | Area of the wall perpendicular to heat flow |
| C. | Material of the wall |
| D. | Temperature difference between the two surfaces of the wall |
| Answer» E. | |
| 112. |
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning frictionfactor) |
| A. | 2f |
| B. | f |
| C. | f/2 |
| D. | f/4 |
| Answer» D. f/4 | |
| 113. |
The equation, Nst = (f/2)/[1 + 5 (Npr - 1) √(f/2)], corresponds to __________ analogy. |
| A. | Von-Karman |
| B. | Reynolds |
| C. | Colburn |
| D. | Prandtl |
| Answer» E. | |
| 114. |
The advantage of using a 1 - 2 shell and tube heat exchanger over a 1 - 1 shell and tube heatexchanger is |
| A. | Lower tube side pressure drop |
| B. | Lower shell side pressure drop |
| C. | Higher tube side heat transfer co-efficient |
| D. | Higher shell side heat transfer co-efficient |
| Answer» D. Higher shell side heat transfer co-efficient | |
| 115. |
The ratio of velocity head to tube side return loss in case of a multipass shell and tube heatexchanger is |
| A. | 2 |
| B. | 1/2 |
| C. | 4 |
| D. | 1/4 |
| Answer» E. | |
| 116. |
Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place |
| A. | Between two bodies in physical contact with each other |
| B. | Between two bodies not in physical contact with each other |
| C. | From one part of a body to the another part of the same body |
| D. | Both 'b' & 'c' |
| Answer» C. From one part of a body to the another part of the same body | |
| 117. |
Which of the following is a case of steady state heat transfer |
| A. | I.C. engine |
| B. | air preheaters |
| C. | heating of building in winter |
| D. | all of the above |
| E. | none of the above. |
| Answer» F. | |
| 118. |
Thermal conductivity of non-metallic amorphous solids with decrease intemperature |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | may increase or decrease depending on temperature |
| E. | unpredictable. |
| Answer» C. remains constant | |
| 119. |
Which of the following is the most controlling factor for the rate of bubble detachmentfrom the hot solid surface? |
| A. | Liquid density |
| B. | Liquid viscosity |
| C. | Hot surface temperature |
| D. | Interfacial tension |
| Answer» E. | |
| 120. |
Electro-magnetic spectrum range, which is important for radiation varies from __________microns. |
| A. | 1 to 100 |
| B. | 0.5 to 50 |
| C. | 10 to 100 |
| D. | 100 to 1000 |
| Answer» C. 10 to 100 | |
| 121. |
Nusselt number is a function of Prandtl number and __________ number of fluid innatural convection heat transfer. |
| A. | Grashoff |
| B. | Biot |
| C. | Stanton |
| D. | Reynolds |
| Answer» B. Biot | |
| 122. |
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 | |
| 123. |
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 | |
| 124. |
Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperatureof Ta°C depends on |
| A. | T1 - T2 |
| B. | T1 - Ta |
| C. | T2 - Ta |
| D. | None of these |
| Answer» E. | |
| 125. |
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors.The film co-efficient of superheated vapor as compared to that of saturated vapor is |
| A. | More |
| B. | Less |
| C. | Some |
| D. | Either more or less; depends on the nature of vapor |
| Answer» D. Either more or less; depends on the nature of vapor | |
| 126. |
According to Wien’s law, the wavelength corresponding to maximum energy isproportion to |
| A. | absolute temperature (T) |
| B. | I2 |
| C. | f |
| D. | t |
| E. | 1/r. |
| Answer» B. I2 | |
| 127. |
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2 . The approximate surface temperature (K) is(Stefan-Boltzmann constant = 5.67 × 10-8 W/m2 .K4 ) |
| A. | 1000 |
| B. | 727 |
| C. | 800 |
| D. | 1200 |
| Answer» B. 727 | |
| 128. |
If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transferco-efficient is |
| A. | Always less than h1 |
| B. | Always between h1 and h2 |
| C. | Always higher than h2 |
| D. | Dependent on metal resistance |
| Answer» C. Always higher than h2 | |
| 129. |
Depending on the radiating properties, body will be transparent when |
| A. | p = 0, x = 0 and a = 1 |
| B. | p=l,x = 0,anda = 0 |
| C. | p = 0, T= l,anda = 0 |
| D. | X = 0, a + p = 1 |
| E. | a = 0,x + p= 1. |
| Answer» D. X = 0, a + p = 1 | |
| 130. |
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wisecondensation are respectively hf and hd, then |
| A. | hf = hd |
| B. | hf > hd |
| C. | hf < hd |
| D. | hf could be greater or smaller than hd |
| Answer» D. hf could be greater or smaller than hd | |
| 131. |
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 | |
| 132. |
When heat is Transferred by molecular collision, it is referred to as heattransfer by |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | scattering |
| E. | convection and radiation. |
| Answer» C. radiation | |
| 133. |
A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s-1 . A 1 - 1shell and tube heat exchanger is available. The best arrangement is |
| A. | Counter flow with process stream on shell side |
| B. | Counter flow with process stream on tube side |
| C. | Parallel flow with process stream on shell side |
| D. | Parallel flow with process stream on tube side |
| Answer» B. Counter flow with process stream on tube side | |
| 134. |
Which of the following is the case of heat transfer by radiation |
| A. | blast furnace |
| B. | heating of building |
| C. | cooling of parts in furnace |
| D. | heat received by a person from fireplace |
| E. | all of the above. |
| Answer» E. all of the above. | |
| 135. |
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is usedto calculate the heat transfer rate. |
| A. | Geometric |
| B. | Arithmetic |
| C. | Logarithmic |
| D. | Either (A), (B) or (C) |
| Answer» D. Either (A), (B) or (C) | |
| 136. |
Depending on the radiating properties, a body will be black when (where a = absorptivity, p == reflectivity, X = transmissivity.) |
| A. | p = 0, x = 0 and a = 1 |
| B. | p= l,T = 0anda = 0 |
| C. | p = 0, x = 1 and a = 0 |
| D. | x = 0, a + p = 0 |
| E. | a = 0,x + p= 1. |
| Answer» B. p= l,T = 0anda = 0 | |
| 137. |
In case of vertical tube evaporator, with increase in liquor level, the overall heat transferco-efficient |
| A. | Increases |
| B. | Decreases |
| C. | Is not affected |
| D. | May increase or decrease; depends on the feed |
| Answer» C. Is not affected | |
| 138. |
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 × 10-3 kg/m2 .s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2 /1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid). |
| A. | 0.5 |
| B. | 0.05 |
| C. | 0.1 |
| D. | 0.15 |
| Answer» D. 0.15 | |
| 139. |
Which of the following parameters of the fluid is not very important, while deciding its routein a shell and tube heat exchanger? |
| A. | Corrosiveness & fouling characteristics |
| B. | Pressure |
| C. | Viscosity |
| D. | Density |
| Answer» E. | |
| 140. |
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» C. Parabola | |
| 141. |
The average heat transfer co-efficient for laminar film condensation on vertical surface isinversely proportional to (where, ΔT = Temperature drop across condensate film) |
| A. | (ΔT)2 |
| B. | √(ΔT) |
| C. | (ΔT)1/4 |
| D. | (ΔT)3/2 |
| Answer» D. (ΔT)3/2 | |
| 142. |
The film thickness for laminar film condensation on vertical surface __________ from topto bottom. |
| A. | Cumulatively increases |
| B. | Cumulatively decreases |
| C. | Remain constant |
| D. | And the surface conductance increase |
| Answer» B. Cumulatively decreases | |
| 143. |
What is the unit of thermal conductivity? |
| A. | Kcal/hr. m2°C |
| B. | Kcal/hr.m.°C |
| C. | Kcal/hr.m |
| D. | Kcal/hr. °C |
| Answer» C. Kcal/hr.m | |
| 144. |
Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a dropletor a spherical particle to a surrounding stagnant film is |
| A. | 0.5 |
| B. | 2 |
| C. | 10 |
| D. | 100 |
| Answer» C. 10 | |
| 145. |
The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m2 . The flux, when the element temperature is increased to 1000°Cfor the same furnace temperature is |
| A. | 11.2 kW/m2 |
| B. | 12.0 kW/m2 |
| C. | 14.6 kW/m2 |
| D. | 16.5 kW/m2 |
| Answer» E. | |
| 146. |
A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day,when it is concentrating from 10% to 25% solids. The water evaporated in kg per day is |
| A. | 6000 |
| B. | 24000 |
| C. | 60000 |
| D. | 48000 |
| Answer» C. 60000 | |
| 147. |
For hot feed, forward feeding as compared to backward feeding results in __________economy. |
| A. | Increased |
| B. | Decreased |
| C. | No effect on |
| D. | None of these |
| Answer» B. Decreased | |
| 148. |
The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj – 2K2 will be |
| A. | I |
| B. | 0.5 |
| C. | 2 |
| D. | 0.25 |
| E. | 4.0 |
| Answer» D. 0.25 | |
| 149. |
When heat is transferred form hot body to cold body, in a straight line, withoutaffecting the intervening medium, it is referred as heat transfer by |
| A. | conduction |
| B. | convection |
| C. | radiation |
| D. | conduction and convection |
| E. | convection and radiation. |
| Answer» D. conduction and convection | |
| 150. |
If all the conditions and dimensions are same, then the ratio of velocity through the tubes ofa double pass heat exchanger to that through the single pass heat exchanger is |
| A. | 1 |
| B. | 2 |
| C. | 1/2 |
| D. | 4 |
| Answer» C. 1/2 | |