Explore topic-wise MCQs in Chemical Engineering.

This section includes 75 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.

51.

The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K 0 + 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.k 2
D. none, ' a ' is just a number
Answer» D. none, ' a ' is just a number
Discussion
52.

The Dietus-Boelter equation for convective leat transfer 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.
Discussion
53.

The critical radius ' r ' of insulation on a pipe is given by

A. r = 2 k / h
B. r = k / h
C. r = k /2 h
D. r = h / k
Answer» C. r = k /2 h
Discussion
54.

A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ' d '. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to

A. d 0.8
B. d -0.2
C. d -1
D. d -1.8
Answer» C. d -1
Discussion
55.

Fouling factor' used in the design of a multipass shell and tube heat exchanger is a

A. non-dimensional factor.
B. factor of safety.
C. conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient.
D. none of these.
Answer» C. conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient.
Discussion
56.

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/m 2 .K. The Biot number is

A. 5.6
B. 0.025
C. 3.5
D. 0.0035
Answer» C. 3.5
Discussion
57.

Heat transfer co-efficient (h 1 ) for liquids increases with

A. increasing temperature.
B. decreasing temperature.
C. decreasing Reynolds number.
D. none of these.
Answer» B. decreasing temperature.
Discussion
58.

The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m 2 . The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0 -8 W/m 2 .K 4 )

A. 1000
B. 727
C. 800
D. 1200
Answer» B. 727
Discussion
59.

Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.

A. 180
B. 970
C. 3.97
D. none of these
Answer» B. 970
Discussion
60.

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, N c = 0.5 x 10 -3 kg/m 2 .s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m 2 /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
Discussion
61.

The Fourier number (defined as a.t/L 2 ) is used in the analysis of problem involving heat transfer by

A. forced convection
B. natural convection
C. transient conduction
D. steady state conduction
Answer» D. steady state conduction
Discussion
62.

If average heat transfer co-efficient is h a and the local coefficient at the end of the plate is h l then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length

A. h a = h l
B. h a = 2 h l
C. h a = 0.5 h l
D. h a = 0.75 h l
Answer» C. h a = 0.5 h l
Discussion
63.

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. t 4
B. T 4
C. 1/ t 4
D. 1/ T 4
Answer» C. 1/ t 4
Discussion
64.

For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, N Pr = Prandtl number)

A. N Pr
B. N Pr 1/3
C. N Pr -1
D. N Pr -1/3
Answer» C. N Pr -1
Discussion
65.

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. 3.06 x l0 5
B. 6.12 x 10 5
C. 7.24 x 10 5
D. 9.08 x 10 5
Answer» B. 6.12 x 10 5
Discussion
66.

The thermal radiation emitted by a body is proportional to T n , where T is its absolute temperature. The value of ' n ' is exactly 4 for

A. black painted bodies only
B. all bodies
C. polished bodies only
D. a black body
Answer» C. polished bodies only
Discussion
67.

For what value of Prandtl number, St = f /2?

A. 1.5
B. 1
C. > 1
D. < 1
Answer» C. > 1
Discussion
68.

A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m 2 .°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be

A. greater than that for uninsulated steam pipe.
B. less than that of the uninsulated steam pipe.
C. equal to that of the uninsulated steam pipe.
D. less than the steam pipe with 5 cms insulation.
Answer» C. equal to that of the uninsulated steam pipe.
Discussion
69.

The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ?T = Temperature drop across condensate film )

A. ( ?T ) 2
B. ?T
C. ( ?T ) 1/4
D. ( ?T ) 3/2
Answer» D. ( ?T ) 3/2
Discussion
70.

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/m 2 . The temperature of the inside wall is - 5°C. The outside wall temperature is

A. 25°C
B. 30°C
C. 35°C
D. 40°C
Answer» D. 40°C
Discussion
71.

Heat produced when a steady state current, I passes through an electrical conductor having resistance, ' R ' is

A. IR
B. I 2 R
C. IR 2
D. I 2 R 2
Answer» C. IR 2
Discussion
72.

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 - 1 shell 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.
Discussion
73.

Hot water (0.01 m 3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m 3 /min) of density 800 kg/m 3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

A. 32
B. 37
C. 45
D. 50
Answer» B. 37
Discussion
74.

The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP) R and the co-efficient of performance as a heat pump (COP) HP are

A. (COP) R = (COP) HP = 0.6
B. (COP) R = 2.5; (COP) HP = 1.5
C. (COP) R = 1.5; (COP) HP = 2.5
D. (COP) R = (COP) HP = 2.5
Answer» D. (COP) R = (COP) HP = 2.5
Discussion
75.

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. 40.5
B. 34.4
C. 26.8
D. 25
Answer» C. 26.8
Discussion