Mass Transfer Mcqs

Q:

For a gas mixture (A+B) equimolar counterdiffusion takes place. Which among the following statements are correct for molar flux?

A) If temperature is doubled, the flux will get halved B) If diffusion length is halved, the flux will get halved
C) If temperature is halved, the flux will get halved D) If temperature is doubled and length is halved, the flux will become four times
 
Answer & Explanation Answer: A) If temperature is doubled, the flux will get halved

Explanation: Not available for this question

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15
Q:

A cylinder of sulfur is kept in a large volume of stagnant air for sublimation. How much time will be required for its complete sublimation?

A) One fourth the time required by sphere of same mass B) Half the time required by a cube of same mass
C) One fourth the time required by a cube of same mass D) Infinite
 
Answer & Explanation Answer: D) Infinite

Explanation: No or negligible mass transfer in stagnant air.

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18
Q:

The molar average velocity of the components in a binary mixture in which they are in equimolar counter diffusion is

A) Equal to mass average velocity B) Zero
C) Always negative D) Always positive
 
Answer & Explanation Answer: B) Zero

Explanation: Not available for this question

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15
Q:

In the previous question if the floor has micro pores and water penetrates the floor at a constant rate of 0.1kg/m²h, what will be the time required for the water layer to disappear?

A) 3.64h B) 4.73h
C) 5.94h D) 2.36h
 
Answer & Explanation Answer: A) 3.64h

Explanation: Combined rate of disappearance= 0.1+9.259*10-5*3600=0.433kg/m²h
Time for disappearance= 1.578/0.433=3.64h.

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27
Q:

A tapered tube of length 8cm and end diameters 2cm and 4cm connects two vessels containing mixtures of A and B. if the tapered tube is replaced with a cylindrical tube of diameter 6cm, what will be the required length of the cylindrical tube to maintain the same flow rate as in the previous case?

A) 8cm B) 16cm
C) 36cm D) 48cm
 
Answer & Explanation Answer: C) 36cm

Explanation: Not available for this question

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17
Q:

Sublimation of a long cylinder made of napthelene occurs in a large volume of stagnant air. The time required for its complete sublimation is

A) infinite B) half the time of sublimation of a sphere of the same mass
C) twice the time of sublimation of a cylinder of the same mass and lengthy/diameter=1 D) half the time of sublimation of a cylinder of the same mass and lengthy/diameter=1
 
Answer & Explanation Answer: A) infinite

Explanation: Not available for this question

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21
Q:

A napthelene hemisphere is placed on a glass plate and a napthelene ball of identical diameter is kept suspended in the stagnant air in two large rooms. The respective shapes of the ball are maintained while they sublime and reduce in size. Which of the following statements are true in this connection?

A) They take the same time for complete sublimation B) The sphere disappears first
C) The hemisphere disappears first D) Nothing definite can be said
 
Answer & Explanation Answer: A) They take the same time for complete sublimation

Explanation: Not available for this question

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15
Q:

At which point of the following locations in the tapered tube of the previous problem is the magnitude of the flux maximum?

A) At the larger diameter end B) At the smaller diameter end
C) Midway in the tube D) Somewhere in between the midway and the larger diameter end
 
Answer & Explanation Answer: B) At the smaller diameter end

Explanation: Not available for this question

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