MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 640 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Harmonic mean temperature difference is given by |
| A. | (ΔT₁ . ΔT₂) |
| B. | .(ΔT₁ . ΔT₂)/(ΔT₁ + ΔT₂) |
| C. | .(ΔT₁ . ΔT₂)(ΔT₁ - ΔT₂) |
| D. | ΔT₁ - ΔT₂)/(ΔT₁ . ΔT₂) |
| Answer» C. .(ΔT₁ . ΔT₂)(ΔT₁ - ΔT₂) | |
| 102. |
Which of the following is directly concerned with the heat transfer? |
| A. | trouhal number |
| B. | herwood number |
| C. | uler number |
| D. | rashoff number |
| Answer» E. | |
| 103. |
In Joule's experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms⁻². Neglecting the heat capacity of agitator, the temperature of water (in °C) is |
| A. | 0.5 |
| B. | 4.4 |
| C. | 6.8 |
| D. | 5 |
| Answer» C. 6.8 | |
| 104. |
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°C for the same furnace temperature is |
| A. | 1.2 kW/m² |
| B. | 2.0 kW/m² |
| C. | 4.6 kW/m² |
| D. | 6.5 kW/m² |
| Answer» E. | |
| 105. |
For what value of Prandtl number, the Col-burn analogy is valid? |
| A. | .06 to 120 |
| B. | .6 to 120 |
| C. | to 103 |
| D. | to 50 |
| Answer» C. to 103 | |
| 106. |
Which of the following has the minimum absorptivity? |
| A. | luminium foil |
| B. | oal dust |
| C. | efractory bricks |
| D. | ron plates |
| Answer» B. oal dust | |
| 107. |
The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (ΔT) between wall and outside bulk. The proportionality is given as |
| A. | ΔT)1/4 |
| B. | ΔT)1/2 |
| C. | ΔT)5/4 |
| D. | ΔT)3/4 |
| Answer» E. | |
| 108. |
The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.°K and thickness 0.16m is 10 W/m². The temperature of the inside wall is - 5°C. The outside wall temperature is |
| A. | 5°C |
| B. | 0°C |
| C. | 5°C |
| D. | 0°C |
| Answer» D. 0°C | |
| 109. |
Graetz number is given by |
| A. | Cp/kL |
| B. | L/mCp |
| C. | Cp/kμ |
| D. | μ/mCp |
| Answer» B. L/mCp | |
| 110. |
Steam side heat transfer co-efficient in an evaporator is in the range of __________ kcal/hr.m²°C. |
| A. | 0-50 |
| B. | 00-500 |
| C. | 000-1500 |
| D. | 000-15000 |
| Answer» E. | |
| 111. |
Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for |
| A. | ube |
| B. | ylinder |
| C. | phere |
| D. | qual for all the three |
| Answer» B. ylinder | |
| 112. |
Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid? |
| A. | leed point |
| B. | ent |
| C. | atchall |
| D. | affle |
| Answer» D. affle | |
| 113. |
Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling? |
| A. | quare pitch |
| B. | riangular pitch |
| C. | iagonal square pitch |
| D. | one of these |
| Answer» C. iagonal square pitch | |
| 114. |
Fouling factor for a heat exchanger is given by (where, U₁ = heat transfer co-efficient of dirty surface U₂ = heat transfer co-efficient of clean surface) |
| A. | ₁ - U₂ |
| B. | /U₁ - 1/U₂ |
| C. | /U₂ - 1/U₁ |
| D. | ₂ - U₁ |
| Answer» C. /U₂ - 1/U₁ | |
| 115. |
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ? |
| A. | ube |
| B. | late |
| C. | phere |
| D. | ll of the above |
| Answer» D. ll of the above | |
| 116. |
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be |
| A. | 5 min |
| B. | 2 min |
| C. | 4 min |
| D. | 1 min |
| Answer» E. | |
| 117. |
The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is __________ law. |
| A. | irchoffs |
| B. | lanck's |
| C. | ien's displacement |
| D. | tefan-Boltzman |
| Answer» B. lanck's | |
| 118. |
The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by |
| A. | x + εy |
| B. | x . εy |
| C. | /εx + 1/εy |
| D. | εx + εy)/(εx + εy - εx . εy) |
| Answer» E. | |
| 119. |
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun? |
| A. | ellow paint |
| B. | hite paint |
| C. | lack paint |
| D. | rey paint |
| Answer» D. rey paint | |
| 120. |
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large. |
| A. | minutes |
| B. | 0 minutes |
| C. | 0 minutes |
| D. | 0 minutes |
| Answer» B. 0 minutes | |
| 121. |
Which type of heat exchanger is preferred for heavy heat loads? |
| A. | ouble pipe |
| B. | late fine |
| C. | eries and parallel set of shell and tube |
| D. | one of these |
| Answer» D. one of these | |
| 122. |
What is the geometric mean of two heat transfer areas A₁ and A₂ ? |
| A. | (A₁ . A₂) |
| B. | (A₁ + A₂) |
| C. | /2 √(A₁ . A₂) |
| D. | √(A₁ . A₂) |
| Answer» B. (A₁ + A₂) | |
| 123. |
Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.) |
| A. | /KA |
| B. | A/x |
| C. | /Ax |
| D. | /Kx |
| Answer» C. /Ax | |
| 124. |
A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m².K. The Biot number is |
| A. | 0.6 |
| B. | 0.025 |
| C. | 0.5 |
| D. | 0.0035 |
| Answer» C. 0.5 | |
| 125. |
A graph between __________ is called Wilson plot. |
| A. | /U Vs . 1/v0.8 |
| B. | /v0.8 Vs . U |
| C. | 0.8 Vs . U |
| D. | /U Vs . 1/V |
| Answer» B. /v0.8 Vs . U | |
| 126. |
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as |
| A. | D)-1.8 |
| B. | D)-0.2 |
| C. | D)0.2 |
| D. | D)1.8 |
| Answer» C. D)0.2 | |
| 127. |
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the |
| A. | igher condensing film co-efficient is desired |
| B. | ondensate is corrosive in nature |
| C. | ower pressure drop through the exchanger is desired |
| D. | emperature of the incoming vapor is very high |
| Answer» C. ower pressure drop through the exchanger is desired | |
| 128. |
Which has the lowest Prandtl number? |
| A. | iquid metal |
| B. | queous solution |
| C. | ater |
| D. | ube oil |
| Answer» B. queous solution | |
| 129. |
Which of the following has the lowest Prandtl number? |
| A. | olten sodium (a coolant used in fast breeder reactor) |
| B. | ater |
| C. | ransformer oil |
| D. | ilute H₂SO₄ |
| Answer» B. ater | |
| 130. |
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids? |
| A. | t high fluid velocity |
| B. | t low velocity |
| C. | hen fluid flows past a smooth surface |
| D. | one of these |
| Answer» B. t low velocity | |
| 131. |
A BTU/hr.ft.2 °F is equal to |
| A. | kcal/hr. m²°C |
| B. | .88 kcal/hr. m.2°C |
| C. | kcal/hr. m².°K |
| D. | one of these |
| Answer» C. kcal/hr. m².°K | |
| 132. |
If h₁ = inner film co-efficient and /h₂ = outer film co-efficient, then the overall heat transfer co-efficient is |
| A. | lways less than h₁ |
| B. | lways between h₁ and h₂ |
| C. | lways higher than h₂ |
| D. | ependent on metal resistance |
| Answer» C. lways higher than h₂ | |
| 133. |
For a laminar flow of fluid in a circular tube, 'h₁' is the convective heat transfer co-efficient at velocity 'V₁'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is |
| A. | .26 h₁ |
| B. | .794 h₁ |
| C. | .574 h₁ |
| D. | .741 h₁ |
| Answer» C. .574 h₁ | |
| 134. |
The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely 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 | |
| 135. |
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m². The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0⁻⁸ W/m².K⁴) |
| A. | 000 |
| B. | 27 |
| C. | 00 |
| D. | 200 |
| Answer» B. 27 | |
| 136. |
Which of the following is concerned with both heat and mass transfer? |
| A. | ewis relationship |
| B. | usselt number |
| C. | utateladze number |
| D. | roude number |
| Answer» B. usselt number | |
| 137. |
Stefan-Boltzman law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K ) |
| A. | ⁴ |
| B. | ⁴ |
| C. | /t⁴ |
| D. | /T⁴ |
| Answer» C. /t⁴ | |
| 138. |
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m⁻².°C-1. The rate of heat loss from the outer surface in W.m-2is |
| A. | 65.4 |
| B. | 67.5 |
| C. | 72.5 |
| D. | 75 |
| Answer» B. 67.5 | |
| 139. |
Overall heat transfer co-efficient of a particular tube is U₁. If the same tube with some dirt deposited on either side has coefficient U₂, then |
| A. | ₁ = U₂ |
| B. | ₂ > U₁ |
| C. | ₁ > U₂ |
| D. | ₁ = dirt factor - U₂ |
| Answer» B. ₂ > U₁ | |
| 140. |
Heat transfer by radiation between two bodies at T₁ & T₂ and in an ambient temperature of Ta°C depends on |
| A. | ₁ - T₂ |
| B. | ₁ - Ta |
| C. | ₂ - Ta |
| D. | one of these |
| Answer» E. | |
| 141. |
What is the thermal conductivity of a perfect heat insulator? |
| A. | ero |
| B. | ne |
| C. | |
| Answer» B. ne | |
| 142. |
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is |
| A. | .06 x l0⁵ |
| B. | .12 x 10⁵ |
| C. | .24 x 10⁵ |
| D. | .08 x 10⁵ |
| Answer» B. .12 x 10⁵ | |
| 143. |
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 x 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 | |
| 144. |
The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is |
| A. | 2.36 |
| B. | 4.36 |
| C. | 120.36 |
| D. | dependent on NRe only |
| Answer» C. 120.36 | |
| 145. |
Economy of a multiple effect evaporator depends upon the |
| A. | heat balance consideration |
| B. | rate of heat transfer |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» B. rate of heat transfer | |
| 146. |
A diathermaneous substance __________ the thermal radiation completely. |
| A. | absorbs |
| B. | reflects |
| C. | transmits |
| D. | none of these |
| Answer» D. none of these | |
| 147. |
Which type of heat exchanger is preferred for heavy heat loads ? |
| A. | Double pipe |
| B. | Plate fine |
| C. | Series and parallel set of shell and tube |
| D. | None of these |
| Answer» D. None of these | |
| 148. |
At constant temperature, the thermal conductivities of gases __________ with rise in pressure. |
| A. | decrease |
| B. | increase |
| C. | remain unchanged |
| D. | may increase or decrease; depends on the pressure |
| Answer» B. increase | |
| 149. |
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 | |
| 150. |
Small scale evaporation is done in a |
| A. | heat exchanger |
| B. | condenser |
| C. | multiple effect evaporator |
| D. | steam jacketed kettle |
| Answer» E. | |