MCQOPTIONS
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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.
| 601. |
Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. |
| A. | laminar |
| B. | transition |
| C. | both 'a' & 'b' |
| D. | highly turbulent |
| Answer» E. | |
| 602. |
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 | |
| 603. |
In case of evaporators, liquid entrainment results primarily due to |
| A. | high vacuum in the evaporator. |
| B. | high evaporation rate. |
| C. | foaming of the solution. |
| D. | high heat transfer rate. |
| Answer» D. high heat transfer rate. | |
| 604. |
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. | ΔT1/2 |
| C. | (ΔT)5/4 |
| D. | (ΔT)3/4 |
| Answer» E. | |
| 605. |
For heat flow through very thick walled cylinder, use____mean radius. |
| A. | arithmetic |
| B. | logarithmic |
| C. | geometric |
| D. | either (a) or (c) |
| Answer» C. geometric | |
| 606. |
Fourier's law applies to the heat transfer by |
| A. | convection |
| B. | radiation |
| C. | conduction |
| D. | all (a), (b) & (c) |
| Answer» D. all (a), (b) & (c) | |
| 607. |
A sphere of radius 'R1' is enclosed in a sphere of radius 'R2'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is |
| A. | 0 |
| B. | R2/(R1+R2) |
| C. | 1 |
| D. | (R1/R2)2 |
| Answer» C. 1 | |
| 608. |
Tubes are held between top and bottom tube sheets in Calenderia 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. | |
| 609. |
Mode of heat transfer involved in the cooling of air cooled internal combustion engine is |
| A. | conduction |
| B. | natural convection |
| C. | forced convection |
| D. | none of these |
| Answer» C. forced convection | |
| 610. |
The number of kg vaporised per kg of steam fed to the evaporator is defined as |
| A. | capacity |
| B. | rate of evaporation |
| C. | economy |
| D. | rate of vaporisation |
| Answer» D. rate of vaporisation | |
| 611. |
__________ paint has the maximum absorption coefficient. |
| A. | Black |
| B. | Yellow |
| C. | White |
| D. | Grey |
| Answer» B. Yellow | |
| 612. |
If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid |
| A. | remains unchanged. |
| B. | increases. |
| C. | increases or decreases depending on number of shell passes. |
| D. | decreases. |
| Answer» E. | |
| 613. |
Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. |
| A. | Grashoff |
| B. | Reynolds |
| C. | both 'a' & 'b' |
| D. | Prandtl & Grashoff |
| Answer» E. | |
| 614. |
Among liquids, water has a comparatively high value of thermal conductivity, due to its |
| A. | low density |
| B. | high viscosity |
| C. | partial ionisation |
| D. | dense structure |
| Answer» D. dense structure | |
| 615. |
Thermal conductivity of a conducting solid material depends upon its |
| A. | temperature |
| B. | porosity |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 616. |
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. | |
| 617. |
Thermal diffusivity is the most important in heat transfer by |
| A. | conduction |
| B. | radiation |
| C. | condensation |
| D. | natural convection |
| Answer» B. radiation | |
| 618. |
The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid. |
| A. | viscosity |
| B. | density |
| C. | thermal conductivity |
| D. | corrosive nature |
| Answer» B. density | |
| 619. |
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the |
| A. | baffle spacing & shell diameter. |
| B. | tube diameter & pitch. |
| C. | viscosity, density & mass velocity of shell side fluid. |
| D. | none of these. |
| Answer» E. | |
| 620. |
Heat waves |
| A. | can not pass through vacuum. |
| B. | travel in straight line. |
| C. | can be reflected by a mirror. |
| D. | both (b) and (c). |
| Answer» E. | |
| 621. |
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 | |
| 622. |
Kirchoff s law applies to __________ radiation. |
| A. | total |
| B. | monochromatic |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 623. |
What is the steam economy in case of a single effect evaporator system ? |
| A. | 1 |
| B. | >1 |
| C. | < 1 |
| D. | 0.1 |
| Answer» D. 0.1 | |
| 624. |
A __________ evaporator employs an annular downtake. |
| A. | basket type |
| B. | horizontal |
| C. | long tube vertical |
| D. | none of these |
| Answer» B. horizontal | |
| 625. |
When vaporisation takes place directly at the heating surface, it is called |
| A. | film boiling |
| B. | nucleate boiling |
| C. | vapour binding |
| D. | none of these |
| Answer» C. vapour binding | |
| 626. |
The Grashoff number is defined as the ratio of the |
| A. | buoyancy to inertial forces. |
| B. | buoyancy to viscous forces. |
| C. | inertial to viscous forces. |
| D. | buoyancy to surface tension forces. |
| Answer» C. inertial to viscous forces. | |
| 627. |
Which of the following is generally considered as opaque surface towards radiations? |
| A. | Gases |
| B. | Solids |
| C. | Liquids |
| D. | Both (b) and (c) |
| Answer» E. | |
| 628. |
Intermittant tube cleaning is possible to be done in case of a __________ evaporator. |
| A. | basket type |
| B. | horizontal tube |
| C. | calendria |
| D. | none of these |
| Answer» B. horizontal tube | |
| 629. |
Air is best heated with steam in a heat exchanger of |
| A. | plate type. |
| B. | double pipe type with fin on steam side. |
| C. | double pipe type with fin on air side. |
| D. | shell and tube type. |
| Answer» D. shell and tube type. | |
| 630. |
Hot water (0.01 m3 /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 m3/min) of density 800 kg/m3 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 | |
| 631. |
In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid |
| A. | varies directly as the area and the LMTD. |
| B. | directly proportional to LMTD and inversely proportional to the area. |
| C. | varies as square of the area. |
| D. | none of these. |
| Answer» B. directly proportional to LMTD and inversely proportional to the area. | |
| 632. |
The equivalent diameter for pressure drop is __________ that for heat transfer. |
| A. | smaller than |
| B. | greater than |
| C. | equal to |
| D. | not related with |
| Answer» B. greater than | |
| 633. |
The critical radius 'r' of insulation on a pipe is given by |
| A. | r = 2k/h |
| B. | r = k/h |
| C. | r = k/2h |
| D. | r = h/k |
| Answer» C. r = k/2h | |
| 634. |
Reason for operating an evaporator in multiple effect is to secure |
| A. | increased steam economy. |
| B. | decreased steam consumption. |
| C. | both (a) and (b). |
| D. | increased capacity. |
| Answer» D. increased capacity. | |
| 635. |
Fouling factor |
| A. | is a dimensionless quantity. |
| B. | does not provide a safety factor for design. |
| C. | accounts for additional resistances to heat flow. |
| D. | none of these. |
| Answer» D. none of these. | |
| 636. |
Black liquor generated during paper manufacture is concentrated in a |
| A. | single effect evaporator. |
| B. | single effect evaporator followed by a crystalliser. |
| C. | multiple effect evaporator. |
| D. | multiple effect evaporators followed by a crystalliser. |
| Answer» D. multiple effect evaporators followed by a crystalliser. | |
| 637. |
The unit of heat transfer co-efficient in SI unit is |
| A. | J/M2°K |
| B. | W/m2°K |
| C. | W/m°K |
| D. | J/m°K |
| Answer» C. W/m¬∞K | |
| 638. |
Choose the correct equation. |
| A. | Nu = (Re) (Pr) (Gz) |
| B. | Nu = (Re) (Pr) (St) |
| C. | Nu = (Re)(Pr) |
| D. | Nu = (Pr)(St) |
| Answer» C. Nu = (Re)(Pr) | |
| 639. |
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. (ŒîT)3/2 | |
| 640. |
Crystal size in a continuous crystalliser depends upon the |
| A. | rate of heat transfer. |
| B. | degree of turbulence. |
| C. | degree of supersaturation. |
| D. | all (a), (b) and (c). |
| Answer» E. | |