Top 550+ Solved Mass Transfer MCQ Questions Answer
Q. In the constant rate period of the rate of drying curve for batch drying,
a. Cracks develop on the surface of the solid
b. Rate of drying decreases abruptly
c. Surface evaporation of unbound moisture occurs
d. None of these
Q. Back-trapping in a distillation column
a. Increases tray efficiency
b. Decreases tray efficiency
c. Reduces pressure drop
d. Is desirable, as it provides improved vapour-liquid contact
Q. Rose oil is extracted from rose leaves using __________ distillation.
a. High pressure
b. Low pressure
c. Extractive
d. Steam
Q. Pick out the wrong statement pertaining to the rotary dryer.
a. Flights (located in the inside shell of rotary dryer) lift the material being dried and shower it down through the current of hot air/gases. It extends from the wall to a distance which is about 8-12% of the inside diameter of shell
b. Hold up of a rotary drier is defined as the fraction of the dryer volume occupied by the solid at any instant. The best performance for rotary drier is obtained, when the hold up is in the range of 0.05 to 0.15
c. Rotary dryer is suitable for drying sticky material
d. Recommended peripheral speed of a rotary drier is in the range of 10 to 30 metres/minute
Q. Which of the following is not a unit of mass transfer co-efficient?
a. Moles transferred/ [(time) (area) (mole fraction)]
b. Moles transferred/ [(time) (area) (mass A/mass B)]
c. Moles transferred/ [(time) (area) (pressure)]
d. None of these
Q. Dry bulb temperature of the gas is __________ the wet bulb temperature.
a. Less than
b. More than
c. Equal to
d. None of these
Q. __________ column is used in gas absorption process.
a. Wetted wall
b. Sieve/perforated tray
c. Bubble cap
d. Packed
Q. The equilibrium liquid composition compared to the vapor composition in case of Azeotropic mixture is
a. More
b. Less
c. Same
d. Either more or less; depends on the system
Q. The diffusion co-efficient in m2/s. of acetic acid in benzene (liquid in liquid) is
a. 2.09 × 10-4
b. 2.09 × 10-5
c. 2.09 × 10-9
d. 2.09 × 10-12
Q. Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled
a. And humidified
b. And dehumidified with increase in wet bulb temperature
c. At the same relative humidity
d. And dehumidified with decrease in wet bulb temperature
Q. The 'shanks system' of leaching (i.e., counter-current multiple contact leaching) is used for
a. Recovery of tannis from the tree barks and woods
b. Leaching sodium nitrate from Chilean nitrate bearing rock
c. Both (A) and (B)
d. Neither (A) nor (B)
Q. The value of Lewis number (Le = Sc/Pr) for air-water vapour system is around
a. 1
b. 0.24
c. 3.97
d. 600
Q. Which of the following employs an accessory known as 'drift eliminator'?
a. Multiple effect evaporator
b. Mechanical draft cooling tower
c. Rotary dryer
d. Rotating disc contactor
Q. Dew point of an air-water vapor mixture
a. Decreases with decrease in pressure
b. At constant humidity & total pressure is fixed
c. Corresponding to any point on the humidity chart is obtained by projecting a line through this point parallel to the temperature axis and to the saturation curve
d. All 'a', 'b' & 'c'
Q. The term "approach" in a cooling tower refers to the difference in the temperature of the
a. Cold water leaving the tower and the wet bulb temperature of the surrounding air
b. Hot water entering the tower and the wet bulb temperature of the surrounding air
c. Hot water entering and the cooled water leaving the cooling tower
d. None of these