MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 854 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 501. |
The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which D is the diffusivity of solute, is |
| A. | D/a |
| B. | D/2a |
| C. | proportional to D |
| D. | dependent on the Reynolds number |
| Answer» E. | |
| 502. |
In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer. |
| A. | The entire amount of C is transferred to solvent B. |
| B. | Less than 2 kg but more than 1 kg of C is transferred to solvent B. |
| C. | Less than 1 kg of C is transferred to B. |
| D. | No amount of C is tranferred to B. |
| Answer» B. Less than 2 kg but more than 1 kg of C is transferred to solvent B. | |
| 503. |
Leaching of coarse solid lumps is also termed as |
| A. | decoction |
| B. | dissolution |
| C. | percolation |
| D. | agitation and settling |
| Answer» D. agitation and settling | |
| 504. |
In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTUOG = overall gas phase height of a transfer unit) |
| A. | straight |
| B. | parallel |
| C. | both (a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 505. |
As the reflux ratio decreases, the |
| A. | separation becomes more efficient. |
| B. | number of plates increases. |
| C. | column diameter increases. |
| D. | none of these. |
| Answer» C. column diameter increases. | |
| 506. |
For absorbing a sparingly soluble gas in a liquid |
| A. | gas side mass transfer co-efficient should be increased. |
| B. | liquid side mass transfer co-efficient should be increased. |
| C. | liquid side mass transfer co-efficient should be decreased. |
| D. | mass transfer co-efficient must be kept constant. |
| Answer» C. liquid side mass transfer co-efficient should be decreased. | |
| 507. |
During drying operation, it is easier to remove the __________ moisture. |
| A. | equilibrium |
| B. | critical |
| C. | unbound |
| D. | bound |
| Answer» D. bound | |
| 508. |
All moisture in a non-hygroscopic material is the __________ moisture. |
| A. | free |
| B. | equilibrium |
| C. | unbound |
| D. | bound |
| Answer» D. bound | |
| 509. |
Surface renewal model of mass transfer was enunciated by |
| A. | Toor and Marchello |
| B. | Fick |
| C. | Danckwerts |
| D. | Stefan |
| Answer» D. Stefan | |
| 510. |
The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called |
| A. | decoction |
| B. | percolation |
| C. | elutriation or elution |
| D. | none of these |
| Answer» D. none of these | |
| 511. |
Danckwerts developed the __________ theory. |
| A. | penetration |
| B. | surface renewal |
| C. | film |
| D. | none of these |
| Answer» C. film | |
| 512. |
Which of the following remains constant during evaporative cooling process with recirculated water supply ? |
| A. | Relative humidity |
| B. | Partial pressure of vapour |
| C. | Wet bulb temperature |
| D. | None of these |
| Answer» D. None of these | |
| 513. |
Ion exchange process is similar to |
| A. | absorption |
| B. | adsorption |
| C. | extraction |
| D. | leaching |
| Answer» C. extraction | |
| 514. |
When a multistage tray tower uses a minimum reflux ratio, it implies |
| A. | infinite trays and maximum reboiler heat load. |
| B. | infinite trays and minimum reboiler heat load. |
| C. | minimum trays and minimum reboiler heat load. |
| D. | minimum trays and maximum reboiler heat load |
| Answer» B. infinite trays and minimum reboiler heat load. | |
| 515. |
With increase in gas rate, the number of transfer units, NtoG, for a fixed degree of absorption by a fixed amount of solvent |
| A. | increases |
| B. | decreases |
| C. | decreases linearly |
| D. | remains unaffected |
| Answer» B. decreases | |
| 516. |
Only small amount of evaporation of water produces large cooling effects because of its |
| A. | large latent heat |
| B. | low viscosity |
| C. | small latent heat |
| D. | none of these |
| Answer» B. low viscosity | |
| 517. |
Sticky material can be dried in a __________ dryer. |
| A. | tray |
| B. | rotary |
| C. | fluidised bed |
| D. | none of these |
| Answer» B. rotary | |
| 518. |
'ADDUCTS' and 'CLATHRATES' are used in case of |
| A. | extractive distillation. |
| B. | crystallisation. |
| C. | absorption. |
| D. | none of these. |
| Answer» C. absorption. | |
| 519. |
In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the$ |
| A. | range is 15°F. |
| B. | approach is 10°F. |
| C. | both (a) & (b). |
| D. | neither (a) nor (b). |
| Answer» D. neither (a) nor (b). | |
| 520. |
In a counter-current liquid extractor |
| A. | both liquids flow at fixed rate. |
| B. | both liquids can have any desired flow rate. |
| C. | only one of the liquids may be pumped at any desired rate. |
| D. | liquid's flow rate depends upon the temperature and pressure. |
| Answer» D. liquid's flow rate depends upon the temperature and pressure. | |
| 521. |
In case of absorption, both the operating and equilibrium lines will be straight for |
| A. | isothermal operation. |
| B. | dilute solutions. |
| C. | dilute solutions and isothermal operation. |
| D. | none of these. |
| Answer» D. none of these. | |
| 522. |
Absorption accompanied by heat evolution results in |
| A. | increased capacity of the absorber. |
| B. | increase in equilibrium solubility. |
| C. | decrease in equilibrium solubility. |
| D. | none of these. |
| Answer» D. none of these. | |
| 523. |
Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. |
| A. | bound |
| B. | unbound |
| C. | critical |
| D. | none of these |
| Answer» B. unbound | |
| 524. |
Desulphurisation of petrol is done in a |
| A. | Bollman extractor |
| B. | rotating disc extractor |
| C. | packed extraction column |
| D. | plate type extraction column |
| Answer» C. packed extraction column | |
| 525. |
Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the |
| A. | mass transfer co-efficient. |
| B. | thermal diffusivity. |
| C. | kinematic viscosity. |
| D. | volumetric diffusivity. |
| Answer» B. thermal diffusivity. | |
| 526. |
At what value of reflux ratio, number of theoretical plates in a distillation column is minimum ? |
| A. | 0 |
| B. | 1 |
| C. | ‚àû |
| D. | < 1 |
| Answer» D. < 1 | |
| 527. |
At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes |
| A. | 1 |
| B. | 0 |
| C. | ‚àû |
| D. | none of these |
| Answer» D. none of these | |
| 528. |
Extraction of pencillin employs a __________ extraction coloumn. |
| A. | centrifugal |
| B. | packed |
| C. | plate |
| D. | None of these. |
| Answer» B. packed | |
| 529. |
For absorbers, high pressure drop results in |
| A. | increased efficiency. |
| B. | decreased efficiency. |
| C. | high operating cost. |
| D. | better gas liquid contact. |
| Answer» D. better gas liquid contact. | |
| 530. |
The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same sytem is |
| A. | 100 |
| B. | 10 |
| C. | 5 |
| D. | 1 |
| Answer» C. 5 | |
| 531. |
Under conditions of flooding in packed tower, the gas pressure drop |
| A. | decreases rapidly |
| B. | increases rapidly |
| C. | remains constant |
| D. | is maximum |
| Answer» E. | |
| 532. |
Decoction refers to the use of solvent |
| A. | at ambient temperature |
| B. | at its boiling point |
| C. | in its vapor form |
| D. | none of these |
| Answer» C. in its vapor form | |
| 533. |
Which of the following processes is not an example of adsorption applied to gaseous separations ? |
| A. | Recovery of valuable solvent vapors from dilute mixture with air and other gases. |
| B. | Dehumidification of air and gas. |
| C. | Removal of objectionable odour and impurities from industrial gases. |
| D. | Decolouration of yellow glycerene. |
| Answer» E. | |
| 534. |
A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids)) |
| A. | M(Xo - XF) |
| B. | M(Xo/XF) |
| C. | M ln(Xo/XF) |
| D. | MXo ln(Xo/XF) |
| Answer» E. | |
| 535. |
Binary distillation involves the mass transfer by __________ at the gas-liquid interface. |
| A. | unidirectional diffusion from liquid to gas phase |
| B. | unidirectional diffusion from gas to liquid phase |
| C. | either 'a' or 'b' |
| D. | a counter diffusion at an almost equal molar rate |
| Answer» E. | |
| 536. |
The suitable evaporator for concentration of foaming liquids is a __________ evaporator. |
| A. | long tube |
| B. | short tube |
| C. | vacuum |
| D. | falling film |
| Answer» B. short tube | |
| 537. |
The temperature of water cooled in cooling tower is always __________ temperature of entering air. |
| A. | more than the wet bulb |
| B. | less than the wet bulb |
| C. | equal to the wet bulb |
| D. | equal to the dry bulb |
| Answer» B. less than the wet bulb | |
| 538. |
In case of constant underflow extraction operation, the __________ at all solute concentration. |
| A. | solids are drained to the same extent |
| B. | ratio of the insoluble to solution is constant |
| C. | both(a) & (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 539. |
Unit operation involved in the prilling of urea is |
| A. | evaporation |
| B. | drying |
| C. | crystallisation |
| D. | both (b) and (c) |
| Answer» E. | |
| 540. |
In saturated gas, the |
| A. | vapour is in equilibrium with the liquid at the gas temperature. |
| B. | vapour is in equilibrium with the liquid at the room temperature. |
| C. | partial pressure of vapour equals the vapour pressure of the liquid at room temperature. |
| D. | none of these. |
| Answer» B. vapour is in equilibrium with the liquid at the room temperature. | |
| 541. |
In case of liquid-liquid binary diffusion, diffusivity of one constituent into another is not dependent on the |
| A. | temperature and pressure |
| B. | concentration |
| C. | nature of the constituents |
| D. | none of these |
| Answer» E. | |
| 542. |
The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp = M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force.) |
| A. | Kc = Kp = Km |
| B. | Kc = Kp/RT = Km . RT/P |
| C. | Kc = Kp . RT = Km . RT/p |
| D. | none of these |
| Answer» D. none of these | |
| 543. |
Laboratory determination of the dif-fusivity of vapor is done by __________ method. |
| A. | wetted wall column |
| B. | Gilliland's |
| C. | Winkel mann's |
| D. | Wike's |
| Answer» D. Wike's | |
| 544. |
For a binary mixture with low relative volatility, continuous rectification to get pure products will require |
| A. | low reflux ratio |
| B. | less number of trays |
| C. | small cross-section column |
| D. | high reflux ratio |
| Answer» E. | |
| 545. |
Plate efficiency in a distillation column is reduced due to the __________ of liquid. |
| A. | entrainment |
| B. | foaming |
| C. | weeping & dumping |
| D. | all (a), (b) & (c) |
| Answer» E. | |
| 546. |
Prandtl number for water at 20°C is about$ |
| A. | 7 |
| B. | 70 |
| C. | 0.7 |
| D. | 150 |
| Answer» B. 70 | |
| 547. |
Relative volatility varies with the concentration of component for an ideal solution. The relative volatity of a binary mixture may be defined as the ratio of vapor pressure of component 'A' to that of component 'B', when |
| A. | only vapor phase follows Raoult's law. |
| B. | only liquid phase obeys Dalton's law. |
| C. | liquid phase obeys Dalton's law and vapor phase obeys Raoult's law. |
| D. | Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law. |
| Answer» E. | |
| 548. |
When the psychometric ratio is __________ then the adiabatic saturation temperature and wet bulb temperature becomes equal. |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | ‚àû |
| Answer» B. < 1 | |
| 549. |
Which of the following is not fixed by the process requirements, in the design of absorbers ? |
| A. | Flow rate of the entering gas. |
| B. | Composition of the entering liquid. |
| C. | Terminal concentrations of gas stream. |
| D. | None of these. |
| Answer» E. | |
| 550. |
In case of an unsaturated mixture of gas and vapor, the percentage saturation is __________ its relative saturation. |
| A. | lower than |
| B. | higher than |
| C. | equal to |
| D. | either (a) or (b), depends on the mixture composition |
| Answer» B. higher than | |