Mass Transfer - Practice Test

(A) For identical gas flow rates, less pressure drop occurs through a plate tower than through a packed tower

(B) Plate column can handle greater liquid loads without flooding than packed column, but the liquid hold up is more in the case of plate column

(C) For the same duty, plate columns weigh less than packed columns

(D) All of the above

(E) In case of liquid-liquid extraction, no separation is possible, if the selectivity of the solvent used is unity

(F) With increase in temperature, the selectivity of the solvent used in solvent extraction decreases

(G) The selectivity of solvent used in solvent extraction is unity at the plait point

(H) All of the above

(I) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non-ideal binary system by distillation

(J) A sharp decrease in pressure drop is an indication of flooding in a distillation coloumn

(K) Solvent used in extractive distillation should be of high volatility

(L) Flash distillation is suitable for separating components which have very close boiling temperature

(M) Dialysis process is used for the production of fresh water from brine

(N) Electrodylsis is used in the manufacture of NaOH

(O) Electrodylsis is used for the refin-ning/purification of petrol

(P) Both B and C

(Q) Bound moisture is removed during constant rate drying period

(R) Free moisture is removed during falling rate drying period

(S) The sum of free moisture and equilibrium moisture in a solid is called the critical moisture

(T) The driving force for mass transfer in a wet solid is its free moisture content

(U) Diffusivity decreases with increase in temperature

(V) Diffusivity increases with increase in molecular weight

(W) Diffusivity increases with the size of the individual molecule

(X) None of these

(Y) The slope of the stripping line is always less than unity

(Z) For a given separation in a binary distillation column, with increase in reflux ratio (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases

([) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux

(\) Kremsor-Brown-Souder's equation is used to calculate the efficiency of a plate tower

(]) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas

(^) The 'Hatta number' is important in problems involving gas absorption without chemical reaction

(_) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion

(`) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

Mass Transfer - Study Mode

[#26] A natural draft cooling tower is filled with wooden grids, which covers about __________ percent of the tower height.

Correct Answer

[#27] The temperature of water cooled in cooling tower is always __________ temperature of entering air.

Correct Answer

[#28] Pick out the correct statement.

Correct Answer

[#29] High pressure at the bottom of a distillation tower handling heat sensitive materials results in

Correct Answer

[#30] In a counter-current extractor, as the axial mixing increases, the extraction efficiency

Correct Answer