Practice Test: Question Set - 01
1. Which of the following psychrometric processes is followed by water vapor laden unsaturated air, when it is passed through solid or liquid adsorbent?
- (A) Cooling
and dehumidification
- (B) Heating
and dehumidification at almost constant wet bulb temperature
- (C) Dehumidification
with dry bulb temperature remaining constant
- (D) None
of these
2. Heat sensitive materials like certain pharmaceuticals and food stuffs can be dried in a/an __________ dryer.
- (A) Indirect
tray
- (B) Spray
- (C) Freeze
- (D) None of
these
3. According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the column.
- (A) 5
- (B) 9
- (C) 12
- (D) 28
4. With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible.
- (A) Increases
- (B) Decreases
- (C) Remain
same
- (D) Increases
linearly
5. During the constant rate period of drying of a solid,
- (A) Increased
air humidity decreases the rate of drying
- (B) Increasing
the air temperature decreases the drying rate
- (C) Surface
evaporation of unbound moisture occurs
- (D) None of
these
6. Large scale drying of wheat is done in a __________ dryer.
- (A) Fluidised
bed
- (B) Spouted bed
- (C) Tray
- (D) Vacuum
rotary
7. Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is
- (A) Insoluble in
the liquid
- (B) Soluble
in the liquid
- (C) Non-ideal
in nature
- (D) At
a fixed temperature
8. With increase in temperature, the leaching rate increases due to
- (A) Decreased
liquid viscosity
- (B) Increased
diffusivity
- (C) Both (a) and
(b)
- (D) Neither (a)
nor (b)
9. As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages
- (A) Increase
- (B) Decrease
- (C) Remain
unchanged
- (D) Can
either increase or decrease, depends on the system
10. 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
11. Large scale drying of sugar is done in a __________ dryer.
- (A) Spouted bed
- (B) Tray
- (C) Rotary
- (D) Truck
12. Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption.
- (A) Lower than
- (B) Higher
than
- (C) Same as
- (D) Either same
or higher than
13. H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in meters) corresponding to an operating line given by, y = 5x + 0.001 is
- (A) 2.0
- (B) 1.56
- (C) 1.0
- (D) 0.56
14. Reboiler is considered as one theoretical plate, because
- (A) Of
the assumption that vapour and liquid leaving the reboiler are in equilibrium
- (B) Vapour
is recycled to the column
- (C) Reboiler
itself contains one plate
- (D) None
of these
15. In an absorption column, the flooding velocity for random packing is __________ that for stacked/regular packing.
- (A) Greater
than
- (B) Smaller
than
- (C) Equal to
- (D) Either
(a), or (b); depends on the type of packing