MCQOPTIONS
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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.
| 401. |
Diffusion in concentrated solutins differs from that in dilute solutions, because of the change in the __________ with the concentration of the solution. |
| A. | degree of ideality |
| B. | viscosity |
| C. | both 'a '& 'b' |
| D. | neither 'a' nor 'b' |
| Answer» D. neither 'a' nor 'b' | |
| 402. |
Weeping in a distillation column |
| A. | increases tray efficiency. |
| B. | provides large interfacial surface for mass transfer. |
| C. | results due to very high gas velocity. |
| D. | results due to very low gas velocity. |
| Answer» E. | |
| 403. |
If mass diffusivity in a mixture is equal to the thermal diffusivity, then the Lewis number is |
| A. | 0 |
| B. | 1 |
| C. | < 1 |
| D. | > 1 |
| Answer» C. < 1 | |
| 404. |
A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state, |
| A. | composition of vapors and that of liquid do not vary throughout the column. |
| B. | reboiler load and condenser load are minimum. |
| C. | the top and bottom compositions are unchanged with and without total reflux. |
| D. | the top and bottom compositions correspond to the maximum enrichment available. |
| Answer» E. | |
| 405. |
Air at a particular humidity is heated in a furnace. The new dew point |
| A. | decreases |
| B. | increases |
| C. | depends on the extent of heating |
| D. | remain unchanged |
| Answer» C. depends on the extent of heating | |
| 406. |
The Schmidt number which is defined as, μ/ρ D, is the ratio of the$ |
| A. | momentum diffusivity to the mass dif-fusivity. |
| B. | thermal diffusivity to the mass diffusivity. |
| C. | momentum diffusivity to the thermal diffusivity. |
| D. | none of these. |
| Answer» B. thermal diffusivity to the mass diffusivity. | |
| 407. |
Small dia distillation column can be a |
| A. | packed column |
| B. | sieve tray |
| C. | bubble cap |
| D. | any of these |
| Answer» B. sieve tray | |
| 408. |
In distillation where q is defined as the moles of liquid flow in the stripping section per mole of feed introduced, for saturated liquid feed |
| A. | q > 1 |
| B. | q < 1 |
| C. | q = 1 |
| D. | q = 0 |
| Answer» D. q = 0 | |
| 409. |
The film penetration model of mass transfer was enunciated by |
| A. | Gilliland |
| B. | Toor and Marchello |
| C. | Stefan |
| D. | Fick |
| Answer» C. Stefan | |
| 410. |
Liquid diffusivity is of the order of __________ cm2 /second. |
| A. | 0.01 |
| B. | 0.1 |
| C. | 10-5 to 10-6 |
| D. | > 1 |
| Answer» D. > 1 | |
| 411. |
If f is defined as above, then which of the following applies to a feed at dew point ? |
| A. | f = 1 |
| B. | f < 1 |
| C. | f > 1 |
| D. | 0 < f < 1 |
| Answer» B. f < 1 | |
| 412. |
In liquid-liquid extraction, the number of phases at plait point is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
| 413. |
The Knudsen diffusivity is dependent on the |
| A. | molecular velocity only. |
| B. | pore radius of the catalyst only. |
| C. | molecular mean free path only. |
| D. | molecular velocity and por radius of the catalyst. |
| Answer» E. | |
| 414. |
Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in |
| A. | decreased solute solubility. |
| B. | large minimum liquid to gas (L/G) ratio. |
| C. | large number of trays. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 415. |
During constant rate drying period, vaporisation rate per unit drying surface area |
| A. | decreases with time. |
| B. | increases with time. |
| C. | does not change with time, |
| D. | does not affect the moisture content of the wet solid. |
| Answer» D. does not affect the moisture content of the wet solid. | |
| 416. |
In steam distillation, the |
| A. | temperature is 100°C. |
| B. | temperature is more than 100° C. |
| C. | product must be immiscible with water. |
| D. | temperature is higher than the boiling point of either component. |
| Answer» D. temperature is higher than the boiling point of either component. | |
| 417. |
With decrease in the throughput (compared with the design capacity) for a bubble cap distillation column, its efficiency |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | may increase or decrease ; depends on individual design |
| Answer» B. decreases | |
| 418. |
In the layout plan for a vacuum distillation unit, operating at 60 mm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be |
| A. | at ground level. |
| B. | 2 metres above the ground. |
| C. | 5 metres above ground. |
| D. | 10 metres above ground. |
| Answer» B. 2 metres above the ground. | |
| 419. |
In case of liquids, the binary diffusivity is proportional to (where, T = temperature) |
| A. | T |
| B. | T |
| C. | T2 |
| D. | 1/T |
| Answer» B. T | |
| 420. |
Co-current absorbers are usually used when the gas to be dissolved in the liquid is |
| A. | sparingly soluble |
| B. | highly soluble |
| C. | a pure substance |
| D. | a mixture |
| Answer» D. a mixture | |
| 421. |
In azeotropic mixture, the equilibrium vapour composition is |
| A. | more than liquid composition. |
| B. | less than liquid composition. |
| C. | same as liquid composition. |
| D. | independent of pressure. |
| Answer» D. independent of pressure. | |
| 422. |
Weight of 1 m3 of humid air as compared to 1 m3 of dry air, under the same conditions, is |
| A. | less |
| B. | more |
| C. | same |
| D. | unpredictable |
| Answer» B. more | |
| 423. |
Flash distillation is suitable for the separation of components |
| A. | having very close boiling points. |
| B. | which form maximum boiling azeotrope. |
| C. | having very wide boiling points. |
| D. | which form minimum boiling azeotrope. |
| Answer» D. which form minimum boiling azeotrope. | |
| 424. |
The wet and 'dry bulb temperature for a vapour-gas mixture are 25°C and 30°C respectively. If the mixture is heated to 45°C at constant pressure, the wet bulb temperature will be __________ °C.$ |
| A. | 25 |
| B. | > 25 |
| C. | < 25 |
| D. | -25 |
| Answer» C. < 25 | |
| 425. |
Heat sensitive materials with very high latent heat of vaporisation may be economically separated using |
| A. | liquid extraction |
| B. | distillation |
| C. | evaporation |
| D. | absorption |
| Answer» B. distillation | |
| 426. |
Large quantity of silica gel is normally dried in a __________ dryer. |
| A. | freeze |
| B. | through circulation |
| C. | rotary vacuum |
| D. | tray |
| Answer» C. rotary vacuum | |
| 427. |
Which of the following is an undesirable property for an absorbing solvent ? |
| A. | Low vapour pressure |
| B. | Low velocity |
| C. | Low freezing point |
| D. | None of these |
| Answer» E. | |
| 428. |
The cooling effect in a cooling tower can be speeded up by |
| A. | increasing the air velocity and area of exposed wet surface. |
| B. | reducing the barometric pressure. |
| C. | reducing the humidity of the air. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 429. |
Can the efficiency of a plate in the distillation tower be greater than 100% ? |
| A. | Yes |
| B. | Normally not; but is possible if infinite number of plates are put. |
| C. | Never |
| D. | Yes ; if the reflux ratio is maximum. |
| Answer» D. Yes ; if the reflux ratio is maximum. | |
| 430. |
Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty ? |
| A. | Grid tray tower |
| B. | Perforated tray tower |
| C. | Wetted wall tower |
| D. | Bubble cap tower |
| Answer» E. | |
| 431. |
Antibiotics are best handled in a |
| A. | Podbielniak extractor. |
| B. | sieve tray contractor. |
| C. | rotating disc contactor. |
| D. | pulsed column extractor. |
| Answer» B. sieve tray contractor. | |
| 432. |
The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity DBA (for component B diffusing in A) for a binary mixture of |
| A. | Newtonion liquids |
| B. | non-Newtonion liquids |
| C. | ideal gases |
| D. | real gases |
| Answer» D. real gases | |
| 433. |
Which of the following adsorbant is used in the refinning of sugar ? |
| A. | Bone charcoal |
| B. | Wood charcoal |
| C. | Silica gel |
| D. | Activated clay |
| Answer» B. Wood charcoal | |
| 434. |
The following plot gives the saturated humidity (He) versus temperature (T).Line joining (H1, T1) and (H2, T2) is the constant enthalpy line. Choose the correct one from among the alternatives A, B, C and D. |
| A. | T1-Dew point temp; T2-Dry bulb temp; T3-Wet bulb temp. |
| B. | T1-Dew point temp; T2-Wet bulb temp; T3-Dry bulb temp. |
| C. | T1-Wet bulb temp; T2-Dry bulb temp; T3-Dew point temp. |
| D. | T1-Dry bulb temp; T2-Wet bulb temp; T3-Dew point temp. |
| Answer» E. | |
| 435. |
A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process ? |
| A. | Flow rate of inlet air |
| B. | Relative humidity of outlet air |
| C. | Humidity of inlet air |
| D. | Temperature of the solid |
| Answer» E. | |
| 436. |
Gaseous diffusivity at atmospheric pressure is of the order of __________ cm2/second. |
| A. | 1 |
| B. | 1 to 5 |
| C. | 5 to 10 |
| D. | > 10 |
| Answer» B. 1 to 5 | |
| 437. |
Advantage of continuous drying over batch drying is that the |
| A. | drying cost per unit weight of dried product is less. |
| B. | product with more uniform moisture content is produced. |
| C. | equipment size required is smaller. |
| D. | all 'a', 'b' & 'c' |
| Answer» E. | |
| 438. |
What is the reflux ratio at total reflux ? |
| A. | Zero |
| B. | Infinity |
| C. | Unity |
| D. | Data insufficient |
| Answer» C. Unity | |
| 439. |
Which of the following mixtures does not form an azeotrope at atmosheric pressure? |
| A. | Water-alcohol |
| B. | Methyl alcohol-acetone |
| C. | Butyl acetate-water |
| D. | None of these |
| Answer» E. | |
| 440. |
Sodium bicarbonate is produced during soda ash manufacture using a __________ tower. |
| A. | plate |
| B. | baffle |
| C. | packed |
| D. | none of these |
| Answer» C. packed | |
| 441. |
Most important factor to be considered in the selection of packings for absorbers is the __________ of packing. |
| A. | size |
| B. | durability |
| C. | porosity |
| D. | cost |
| Answer» D. cost | |
| 442. |
Components, having widely different boiling point in a binary mixture, can be separated using __________ distillation. |
| A. | molecular |
| B. | extractive |
| C. | steam |
| D. | simple |
| Answer» E. | |
| 443. |
In McCabe-Thiele method, at infinite reflux ratio |
| A. | the overhead product is minimum. |
| B. | both the operating lines coincide with diagonal. |
| C. | both (a) and (b). |
| D. | neither (a) nor (b). |
| Answer» B. both the operating lines coincide with diagonal. | |
| 444. |
The most common packing used in industrial operations is __________ rings. |
| A. | raschig |
| B. | lessing |
| C. | cross-partition |
| D. | single spiral |
| Answer» B. lessing | |
| 445. |
Steady state equimolal counter diffusion is encountered in |
| A. | separation of a binary mixture by distillation. |
| B. | absorption of NH3 from air by water. |
| C. | all liquid-liquid diffusion systems. |
| D. | all liquid-solid diffusion systems. |
| Answer» B. absorption of NH3 from air by water. | |
| 446. |
If a two phase system is in physical equilibrium; then it means that, the |
| A. | escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from vapor phase to liquid phase. |
| B. | temperature of the liquid phase is equal to that of the vapor phase. |
| C. | total pressure throughout the liquid phase is equal to that throughout the vapor phase. |
| D. | all (a), (b) and (c). |
| Answer» E. | |
| 447. |
JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by |
| A. | Nsh = 2 |
| B. | Nst = 2 |
| C. | Nsc = 2 |
| D. | none of these |
| Answer» B. Nst = 2 | |
| 448. |
Azeotropic distillation is employed to separate |
| A. | constant boiling mixture. |
| B. | high boiling mixture. |
| C. | mixture with very high relative volatility. |
| D. | heat sensitive materials. |
| Answer» B. high boiling mixture. | |
| 449. |
At what percentage (by volume) of alcohol composition, it forms an azeotrope with water ? |
| A. | 90 |
| B. | 91.5 |
| C. | 95 |
| D. | 99 |
| Answer» D. 99 | |
| 450. |
Separation of two volatile liquids by distillation makes use of their |
| A. | selectivity |
| B. | relative volatility |
| C. | solubility |
| D. | density difference |
| Answer» C. solubility | |