MCQOPTIONS
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MCQOPTIONS
This section includes 482 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 451. |
In a heat exchanger with steam outside the tubes, a liquid gets heated to 45°C, when its flow velocity in the tubes is 2 m/s. If the flow velocity is reduced to 1 m/s, other things remaining the same, the temperature of the exit liquid will be$ |
| A. | Less than 45°C |
| B. | More than 45°C |
| C. | Equal to 45°C |
| D. | Initially decreases and remains constant thereafter |
| Answer» C. Equal to 45¬¨‚àûC | |
| 452. |
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. | |
| 453. |
Which area is used in case of heat flow by conduction through a cylinder? |
| A. | Logarithmic mean area |
| B. | Arithmetic mean area |
| C. | Geometric mean area |
| D. | None of these |
| Answer» B. Arithmetic mean area | |
| 454. |
Which of the following is unimportant in forced convection? |
| A. | Reynolds number |
| B. | Prandtl number |
| C. | Grashhoff number |
| D. | None of these |
| Answer» D. None of these | |
| 455. |
At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical? |
| A. | 0.5 |
| B. | 1 |
| C. | 1.5 |
| D. | 80 |
| Answer» C. 1.5 | |
| 456. |
Which is the most suitable for the concentration of foamy & frothy liquors? |
| A. | Agitated film evaporator |
| B. | Long tube vertical evaporator |
| C. | Open pan evaporator |
| D. | None of these |
| Answer» C. Open pan evaporator | |
| 457. |
Which of the following has maximum thermal conductivity? |
| A. | Iron |
| B. | Coal |
| C. | Nitrogen |
| D. | Tar |
| Answer» B. Coal | |
| 458. |
Choose the most important factor on which the heat conducted through a wall in a unit time 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. | |
| 459. |
In the equation Q = UAΔt; Δt is$ |
| A. | Geometric mean temperature difference |
| B. | Arithmetic mean temperature difference |
| C. | Logarithmic mean temperature difference |
| D. | The difference of average bulk temperatures of hot and cold fluids |
| Answer» D. The difference of average bulk temperatures of hot and cold fluids | |
| 460. |
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 | |
| 461. |
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. | Higher condensing film co-efficient is desired |
| B. | Condensate is corrosive in nature |
| C. | Lower pressure drop through the exchanger is desired |
| D. | Temperature of the incoming vapor is very high |
| Answer» C. Lower pressure drop through the exchanger is desired | |
| 462. |
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 l0⁵ |
| B. | 6.12 x 10⁵ |
| C. | 7.24 x 10⁵ |
| D. | 9.08 x 10⁵ |
| Answer» B. 6.12 x 10‚Äö√Ö¬µ | |
| 463. |
Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity? |
| A. | Aluminium foil |
| B. | Refractory bricks |
| C. | Iron plate |
| D. | Coke breeze |
| Answer» E. | |
| 464. |
Which of the following has the highest thermal conductivity? |
| A. | Brick |
| B. | Air |
| C. | Water |
| D. | Silver |
| Answer» E. | |
| 465. |
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 |
| Answer» B. 970 | |
| 466. |
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 | |
| 467. |
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid. |
| A. | Nucleate |
| B. | Pool |
| C. | Low pressure |
| D. | None of these |
| Answer» C. Low pressure | |
| 468. |
jH factor for heat transfer depends upon the __________ number. |
| A. | Biot |
| B. | Nusselt |
| C. | Reynolds |
| D. | Prandtl |
| Answer» D. Prandtl | |
| 469. |
Steam side heat transfer co-efficient in an evaporator is in the range of __________ kcal/hr.m²°C.$ |
| A. | 10-50 |
| B. | 100-500 |
| C. | 1000-1500 |
| D. | 5000-15000 |
| Answer» E. | |
| 470. |
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. | 11.2 kW/m² |
| B. | 12.0 kW/m² |
| C. | 14.6 kW/m² |
| D. | 16.5 kW/m² |
| Answer» E. | |
| 471. |
A BTU/hr.ft.2 °F is equal to$ |
| A. | 1 kcal/hr. m²°C |
| B. | 4.88 kcal/hr. m.2°C |
| C. | 1 kcal/hr. m².°K |
| D. | None of these |
| Answer» C. 1 kcal/hr. m¬¨‚â§.¬¨‚àûK | |
| 472. |
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to$ |
| A. | Heat the water from 0°C to 100°C |
| B. | Evaporate the water |
| C. | To superheat the steam |
| D. | Data insufficient, can |
| Answer» C. To superheat the steam | |
| 473. |
In which mode of heat transfer, the Biot number is important? |
| A. | Transient heat conduction |
| B. | Natural convection |
| C. | Forced convection |
| D. | Radiation |
| Answer» B. Natural convection | |
| 474. |
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 | |
| 475. |
In a backward feed multiple effect evaporator |
| A. | Feed is introduced in the first effect |
| B. | Feed flows from low pressure to high pressure |
| C. | No pumps are required between successive effects |
| D. | None of these |
| Answer» C. No pumps are required between successive effects | |
| 476. |
A sphere of radius 'R‚ÇÅ' is enclosed in a sphere of radius 'R‚ÇÇ'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is# |
| A. | 0 |
| B. | R‚ÇÇ/(R‚ÇÅ+R‚ÇÇ) |
| C. | 1 |
| D. | (R‚ÇÅ/R‚ÇÇ)2 |
| Answer» C. 1 | |
| 477. |
Reynold's analogy states that (where, St = Stanton number f = friction factor) |
| A. | St = f/2 |
| B. | St = f/4 |
| C. | St = 4f |
| D. | St = f1/2 |
| Answer» B. St = f/4 | |
| 478. |
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time# |
| A. | t = 283 s |
| B. | t = 356 s |
| C. | t = 400 s |
| D. | t = 800 s |
| Answer» E. | |
| 479. |
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 | |
| 480. |
The Fourier number (defined as a.t/L²) 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 | |
| 481. |
Heat transfer by radiation between two bodies at T₁ & T₂ and in an ambient temperature of Ta°C depends on# |
| A. | T‚ÇÅ - T‚ÇÇ |
| B. | T‚ÇÅ - Ta |
| C. | T‚ÇÇ - Ta |
| D. | None of these |
| Answer» E. | |
| 482. |
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 | |