Practice Test: Question Set - 09
1. The dew point of an unsaturated gas-vapor mixture does not depend upon the __________ of the mixture.
- (A) Composition
- (B) Temperature
- (C) Total pressure
- (D) All (a), (b) and (c)
2. 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)
3. The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid).
- (A) √T
- (B) T
- (C) T2
- (D) T3
4. In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is
- (A) Equal to the heat of
formation of surface compound
- (B) Equal to the heat of
wetting
- (C) Zero
- (D) Called integral heat
of adsorption
5. The critical moisture content in case of drying indicates the __________ rate period.
- (A) Beginning of falling
- (B) Beginning of constant
- (C) End of falling
- (D) None of these
6. Pick out the wrong statement.
- (A) The binary
diffusivity in liquids is of the order of 10-5 cm2/sec
- (B) Molecular diffusion
in solid is much faster than that in liquids
- (C) Particles movement
from higher concentration to lower concentration takes place in diffusion
process
- (D) According to
Poiseuille's law, the permeability decreases with increase in temperature for
flow of a gas through a given capillary
7. Humidity chart is useful for the solution of problems concerning condensation, vaporization and air conditioning. At a given dry bulb temperature, value of humidity obtained from the humidity chart directly, is in terms of __________ humidity.
- (A) Molal
- (B) Relative
- (C) Percentage
- (D) None of these
8. Separation of two volatile liquids by distillation makes use of their
- (A) Selectivity
- (B) Relative volatility
- (C) Solubility
- (D) Density difference
9. Powdery materials can be guarded against caking tendency on storage by
- (A) Providing irregular
grain size
- (B) Providing minimum
percentage of voids
- (C) Having maximum
possible points of contact
- (D) None of these
10. The minimum liquid rate to be used in an absorber corresponds to an operating line
- (A) Of slope = 1
- (B) Of slope = 0.1
- (C) Tangential to the
equilibrium curve
- (D) None of these
11. Leaching of uranium ore and gold ore is done in
- (A) Centrifugal extractor
- (B) Pachuca tanks
- (C) Bollman extractor
- (D) None of these
12. The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is
- (A) 0
- (B) ∞
- (C) -ve
- (D) +ve
13. For a ternary mixture, in which equilateral triangular co-ordinate is used in leaching and extraction, a __________ of the equilateral triangular co-ordinates.
- (A) Binary mixture is
represented by the apex
- (B) Binary mixture is
represented by any point inside
- (C) Ternary mixture is
represented by the sides
- (D) Pure component is
represented by the apex
14. In a gas-liquid absorption column, for obtaining the maximum absorption efficiency
- (A) Liquid stream should
be distributed uniformly
- (B) Gas stream should be
distributed uniformly
- (C) Both gas as well as
liquid streams should be distributed uniformly
- (D) By passing should be
completely avoided
15. To get high tray efficiency
- (A) Interfacial surface
between liquid and gas phase should be large
- (B) Time of contact
between the two phases should be less
- (C) Gas velocity should
be very low
- (D) Liquid entrainment
should be severe
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