Mass Transfer MCQs Archives

51. Unsaturated air (with dry and wet bulb temperatures being 35 and 25°C respectively) is passed through water spray chamber maintained at 35°C. The air will be

Cooled

Humidified

Both A & B

Dehumidified

✅ The correct answer is option B.

52. Unsaturated air (with dry bulb and wet bulb temperatures being 45°C and 25°C respectively) is passed through a water spray chamber maintained at 23°C. The air will be cooled and

Humidified with wet bulb temperature decreasing

Humidified at constant wet bulb temperature

Dehumidified

None of these

✅ The correct answer is option A.

53. For water-ethanol system, the minimum reflux ratio

Is computed from the slope of the upper operating line that is tangent to the equilibrium curve

Is computed from the intercept of the operating line

Cannot be computed

Is the optimum reflux ratio

✅ The correct answer is option A.

54. In extraction, as the temperature increases, the area of hetrogeneity (area covered by binodal curve)

Decreases

Increases

Remains unchanged

None of these

✅ The correct answer is option A.

55. Absorption accompanied by heat evolution results in

Increased capacity of the absorber

Increase in equilibrium solubility

Decrease in equilibrium solubility

None of these

✅ The correct answer is option C.

56. The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases ‘A’ and ‘B’ is

∞

0.5

✅ The correct answer is option B.

57. Prandtl number for water at 20°C is about

0.7

150

✅ The correct answer is option A.

58. If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that

The system comprises of partially mis-cible liquids

The system comprises of miscible liquids

The system comprises of an azeotrope

On heating, a vapor phase will appear ; while on cooling, a solid phase will appear

✅ The correct answer is option D.

59. Design calculation for multiple component distillation is done by

Ponchon-Savarit method

Mccabe-Thiele method

Enthalpy concentration method

Tray to tray calculations

✅ The correct answer is option D.

60. Which of the following is an undesirable characteristic for the solvent used in gas absorption?

Low vapor pressure

Low viscosity

High gas solubility

None of these

✅ The correct answer is option D.