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MCQOPTIONS
This section includes 8247 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 3851. |
Kirchoff's law is applicable to |
| A. | monochromatic radiation only |
| B. | total radiation only |
| C. | both (a) and (b) |
| D. | only volumes and not to surfaces |
| Answer» D. only volumes and not to surfaces | |
| 3852. |
In a forward feed multiple effect evaporator, the pressure is |
| A. | highest in last effect |
| B. | lowest in last effect |
| C. | same in all effects |
| D. | dependent on the number of effects |
| Answer» C. same in all effects | |
| 3853. |
In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will |
| A. | increase |
| B. | decrease |
| C. | remain unchanged |
| D. | either increase or decrease; depends on the coolant flow rate |
| Answer» D. either increase or decrease; depends on the coolant flow rate | |
| 3854. |
Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212 F may be around __________ BTU. |
| A. | 180 |
| B. | 970 |
| C. | 3.97 |
| D. | data insufficient, can't be predicted |
| Answer» B. 970 | |
| 3855. |
__________ heat exchanger is used for chilling oil to be dewaxed. |
| A. | U-tube |
| B. | Double pipe |
| C. | Fixed tube |
| D. | Floating head |
| Answer» C. Fixed tube | |
| 3856. |
It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is |
| A. | > 0.75 |
| B. | < 0.75 |
| C. | < 0.50 |
| D. | < 0.25 |
| Answer» C. < 0.50 | |
| 3857. |
In sub-cooled boiling, |
| A. | temperature of the heating surface is less than the boiling point of the liquid. |
| B. | temperature of the heating surface is more than the boiling point of the liquid. |
| C. | bubbles from heating surface are absorbed by the mass of the liquid. |
| D. | very large vapour space is necessary. |
| Answer» C. bubbles from heating surface are absorbed by the mass of the liquid. | |
| 3858. |
With increase in temperature, the thermal conductivity of a gas |
| A. | increases. |
| B. | decreases. |
| C. | remains same. |
| D. | may increase or decrease depending on the type of gas. |
| Answer» B. decreases. | |
| 3859. |
If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor. |
| A. | increase |
| B. | decrease |
| C. | not affect |
| D. | increase the condensing film co-efficient as well as |
| Answer» C. not affect | |
| 3860. |
Prandtl and Reynold's analogies are identical for Prandtl number value of |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» D. 5 | |
| 3861. |
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50 C in industrial practice mainly to avoid |
| A. | its evaporation loss |
| B. | excessive corrosion |
| C. | uneconomic LMTD |
| D. | decrease in heat exchanger efficiency |
| Answer» C. uneconomic LMTD | |
| 3862. |
In evaporators, lowering the feed temperature |
| A. | increases the heating area required. |
| B. | reduces the economy. |
| C. | both (a) and (b). |
| D. | decreases the heating area required. |
| Answer» D. decreases the heating area required. | |
| 3863. |
The purpose of floating head in a heat exchanger is to |
| A. | avoid buckling of tubes. |
| B. | provide support for tubes. |
| C. | decrease the pressure drop. |
| D. | facilitate its lengthening, if needed. |
| Answer» B. provide support for tubes. | |
| 3864. |
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. | 15 min |
| B. | 22 min |
| C. | 44 min |
| D. | 51 min |
| Answer» E. | |
| 3865. |
Tube expansion allowances exist in __________ heat exchanger. |
| A. | multipass fixed tube sheet |
| B. | U-tube |
| C. | single pass fixed tube sheet |
| D. | none of these |
| Answer» C. single pass fixed tube sheet | |
| 3866. |
Agitated film evaporator is suitable for concentrating __________ liquids. |
| A. | foaming |
| B. | viscous |
| C. | very thin |
| D. | corrosive |
| Answer» C. very thin | |
| 3867. |
The thickness of condensate layer in filmwise condensation depends on the |
| A. | condensation rate |
| B. | surface configuration |
| C. | liquid flow rate from the surface |
| D. | all (a), (b) and (c) |
| Answer» E. | |
| 3868. |
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface tempeature follows __________ law. |
| A. | parabolic |
| B. | hyperbolic |
| C. | linear |
| D. | logarithmic |
| Answer» B. hyperbolic | |
| 3869. |
View factor is important in heat transfer by |
| A. | steady state conduction |
| B. | natural convection |
| C. | forced convection |
| D. | radiation |
| Answer» E. | |
| 3870. |
The advantage of using a 1 - 2 shell and tube heat exchanger over a 1 - 1 shell and tube heat exchanger 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. | |
| 3871. |
For a multipass shell and tube heat exchanger, the LMTD correction factor is always |
| A. | 1 |
| B. | > 1 |
| C. | < 1 |
| D. | between 1 & 2 |
| Answer» D. between 1 & 2 | |
| 3872. |
If heat transfer rate varies with the time, it is termed as |
| A. | forced convection |
| B. | steady state conduction |
| C. | monochromatic radiation |
| D. | none of these |
| Answer» E. | |
| 3873. |
Nusselt number is the ratio of the |
| A. | temperature gradient of the wall to that across the entire pipe. |
| B. | temperature difference to the temperature gradient at the wall. |
| C. | heat flux at the wall to that across the entire pipe. |
| D. | none of these |
| Answer» D. none of these | |
| 3874. |
Prandtl number is the ratio of |
| A. | momentum diffusivity to mass diffusivity. |
| B. | momentum diffusivity to thermal diffusivity. |
| C. | thermal diffusivity to mass diffusivity. |
| D. | thermal diffusivity to momentum diffusivity. |
| Answer» C. thermal diffusivity to mass diffusivity. | |
| 3875. |
Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger ? |
| A. | Tube side pressure drop and the heat transfer rate. |
| B. | Convective heat transfer co-efficient. |
| C. | Effective tube surface area for convective heat transfer. |
| D. | All (a) (b) and (c). |
| Answer» E. | |
| 3876. |
Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator? |
| A. | Long vertical evaporator |
| B. | Horizontal tube evaporator |
| C. | Agitated film evaporator |
| D. | Calenderia vertical tube evaporator |
| Answer» D. Calenderia vertical tube evaporator | |
| 3877. |
"The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law. |
| A. | Kirchoffs |
| B. | Planck's |
| C. | Wien's displacement |
| D. | Stefan-Boltzman |
| Answer» B. Planck's | |
| 3878. |
The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are |
| A. | Re.Gz |
| B. | Nu, Pr |
| C. | Nu, Pr, Re |
| D. | Nu, Gz |
| Answer» E. | |
| 3879. |
Heat transfer rate described by Fourier's law will decrease, if the __________ increases. |
| A. | thermal conductivity |
| B. | thickness |
| C. | temperature difference |
| D. | heat transfer area |
| Answer» C. temperature difference | |
| 3880. |
A black body does not __________ radiation. |
| A. | absorb or emit |
| B. | refract |
| C. | reflect |
| D. | both(b) & (c) |
| Answer» E. | |
| 3881. |
The capacity of double-effect evaporator is less than half of the capacity of two single effects, each of which is operating over same terminal temperature difference, when the |
| A. | solution has an elevation of boiling point. |
| B. | evaporators operate under vacuum. |
| C. | evaporators opreate at atmospheric pressure. |
| D. | none of these. |
| Answer» B. evaporators operate under vacuum. | |
| 3882. |
The main purpose of providing fins on heat transfer surface is to increase the |
| A. | temperature gradient. |
| B. | mechanical strength of the equipment. |
| C. | heat transfer area. |
| D. | heat transfer co-efficient. |
| Answer» D. heat transfer co-efficient. | |
| 3883. |
Boiling point of a solution according to Duhring's rule is a linear function of the __________ of water. |
| A. | boiling point (at the same pressure) |
| B. | viscosity |
| C. | density |
| D. | thermal conductivity |
| Answer» B. viscosity | |
| 3884. |
The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances. |
| A. | average |
| B. | geometric mean |
| C. | product |
| D. | sum |
| Answer» E. | |
| 3885. |
At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ? |
| A. | 0.5 |
| B. | < 0.5 |
| C. | > 0.6 |
| D. | < 0.1 |
| Answer» D. < 0.1 | |
| 3886. |
The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is |
| A. | 2 |
| B. | 1/2 |
| C. | 4 |
| D. | 1/4 |
| Answer» E. | |
| 3887. |
Terminal point temperature differences between fluids in case of a heat exchanger is termed as |
| A. | approach. |
| B. | log mean temperature difference. |
| C. | arithmetic mean temperature difference. |
| D. | geometric mean temperature difference. |
| Answer» B. log mean temperature difference. | |
| 3888. |
The advantage of backward feed multiple effect evaporators over forward feed units is that |
| A. | heat sensitive material can be handled. |
| B. | there is no additional cost of pumping. |
| C. | most concentrated liquid is at highest temperature. |
| D. | equal heat transfer co-efficients exist in various effects. |
| Answer» D. equal heat transfer co-efficients exist in various effects. | |
| 3889. |
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ? |
| A. | Liquid density |
| B. | Liquid viscosity |
| C. | Hot surface temperature |
| D. | Interfacial tension |
| Answer» E. | |
| 3890. |
Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger ? |
| A. | Corrosiveness |
| B. | Fouling characteristic |
| C. | Viscosity |
| D. | None of these |
| Answer» E. | |
| 3891. |
Thermal conductivities of most of the liquids __________ with rise in temperature. |
| A. | increases |
| B. | decreases |
| C. | remains unchanged |
| D. | may increase or decrease; depends on the liquid |
| Answer» C. remains unchanged | |
| 3892. |
A metal ball of radius 0.1 m at a uniform temperature of 90 C is left in air at 30 C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60 C is |
| A. | 555 |
| B. | 55.5 |
| C. | 0.55 |
| D. | 0.15 |
| Answer» E. | |
| 3893. |
Unsteady state heat conduction occurs, when |
| A. | temperature distribution is independent of time. |
| B. | temperature distribution is dependent on time. |
| C. | heat flows in one direction only. |
| D. | three dimensional heat flow is concerned. |
| Answer» C. heat flows in one direction only. | |
| 3894. |
What is the absorptivity of a black body ? |
| A. | 1 |
| B. | 0 |
| C. | 0.78 |
| D. | 0.95 |
| Answer» B. 0 | |
| 3895. |
Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called |
| A. | radiation |
| B. | natural convection |
| C. | forced convection |
| D. | conduction |
| Answer» D. conduction | |
| 3896. |
Baffle spacing |
| A. | is not the same as baffle pitch. |
| B. | should be less than one fifth the diameter of the shell. |
| C. | should be less than the inside diameter of the shell. |
| D. | none of these. |
| Answer» D. none of these. | |
| 3897. |
Boiling point elevation of a solution of NaOH |
| A. | increases rapidly with temperature rise. |
| B. | is almost independent of temperature. |
| C. | is almost independent of pressure. |
| D. | both (b) and (c). |
| Answer» E. | |
| 3898. |
Water is normally used as a coolant in the heat exchange equipments mainly because ofits |
| A. | abundance & high heat capacity |
| B. | low density |
| C. | low viscosity |
| D. | high fluidity |
| Answer» B. low density | |
| 3899. |
The rate of emission of radiation by a body does not depend upon the |
| A. | wavelength of radiation. |
| B. | surface temperature of the body. |
| C. | nature of the surface. |
| D. | shape and porosity of the body. |
| Answer» E. | |
| 3900. |
Which of the following has maximum thermal conductivity at the same temperature? |
| A. | Steel |
| B. | Petrol |
| C. | Air |
| D. | All have the same conductivity |
| Answer» B. Petrol | |