Chemical Engineering Gate Yearwise 


Chemical Engineering Gate 2012 Questions with Answer

Ques 53 GATE 2012

A thermocouple having a linear relationship between 0°C and 350°C shows an emf of zero and 30.5 mV, respectively at these two temperatures. If the cold junction temperature is shifted from 0°C to 30°C then the emf correction (in mV) is

A

3.13

B

2.92

C

2.61

D

2.02


(c) is the correct answer.

Ques 54 GATE 2012

The characteristic equation for a system is s3+9s2+26s+12(2+Kc)=0. Using the Routh test, the value of Kc that will keep the system on the verge of instability is

A

20.9

B

18.4

C

17.5

D

15.3


(c) is the correct answer.

Ques 55 GATE 2012

The block diagram of a system with a proportional controller is shown below

A unit step input is introduced in the set point. The value of Kc to provide a critically damped response for U=0 τp=8 and τm=1 is

A

3.34

B

2.58

C

1.53

D

1.12


(c) is the correct answer.

Ques 56 GATE 2012

The reaction A(liq)+B(gas)→C(liq)+D(gas) is carried out in a reactor followed by a separator as shown below

Notation:
Molar flow rate of fresh B is FFB
Molar flow rate of A is FA
Molar flow rate of recycle gas is FRG
Mole fraction of B in recycle gas is YRB
Molar flow rate of purge gas is FPG
Molar flow rate of C is FC
Here, FFB=2 mol/s; FA=1 mol/s, FB/FA=5 and A is completely converted.
If YRB=0.3. the ratio of recycle gas to purge gas (FRG/FPG) is

A

2

B

5

C

7

D

10


(b) is the correct answer.

Ques 57 GATE 2012

The reaction A(liq)+B(gas)→C(liq)+D(gas) is carried out in a reactor followed by a separator as shown below

Notation:
Molar flow rate of fresh B is FFB
Molar flow rate of A is FA
Molar flow rate of recycle gas is FRG
Mole fraction of B in recycle gas is YRB
Molar flow rate of purge gas is FPG
Molar flow rate of C is FC
Here, FFB=2 mol/s; FA=1 mol/s, FB/FA=5 and A is completely converted.
If the ratio of recycle gas to purge gas (FRG/FPG) is 4 then YRB is

A

3/8

B

2/5

C

1/2

D

3/4


(a) is the correct answer.

Ques 58 GATE 2012

In the McCabe-Thiele diagram, if the x-coordinate of the point of intersection of the q-line and the vapor-liquid equilibrium curve is greater than the x-coordinate of the feed point, then the quality of the feed is

A

super-heated vapor

B

liquid below bubble point

C

saturated vapor

D

saturated liquid


(b) is the correct answer.

Ques 59 GATE 2012

For which of the following combinations, does the absorption operation become gas-film controlled?
P. The solubility of gas in the liquid is very high
Q. The solubility of gas in the liquid is very low
R. The liquid-side mass transfer coefficient is much higher than the gas-side mass transfer coefficient
S. The liquid-side mass transfer coefficient is much lower than the gas-side mass transfer coefficient

A

P & Q

B

P & R

C

P & S

D

Q & R


(b) is the correct answer.

Ques 60 GATE 2012

Consider the drying operation shown in the figure below for a solid loading (dry basis) of 50 kg/m2 with a constant drying rate of 5 kg/m2. The falling rate of drying is linear with moisture content.


The drying time (in hrs) required to reduce an initial moisture content of 25% to a final moisture content of 2% is

A

1.55

B

1.75

C

3.25

D

4.55


(c) is the correct answer.

Ques 61 GATE 2012

An equimolar mixture of A and B (A being more volatile) is flash distilled continuously at a feed rate of 100 kmol/h. such that the liquid product contains 40 mol % of A. If the relative volatility is 6, then the vapor product, in kmol/h is

A

10

B

20

C

25

D

45


(c) is the correct answer.

Ques 62 GATE 2012

A counter-current extraction column is designed to remove 99% of solute C from a solution of solvent A and solute C using pure solvent B. The initial concentration of solute in the solution of A+C is 20 wt%, and the total flow of solution is 1000 kg/h. If the equilibrium relationship is Y=2X, where Y=mass of C/mass of A and X=mass of C/mass of B.
The minimum flow rate of solvent B required (in kg/h) is

A

1454

B

1584

C

1676

D

1874


(b) is the correct answer.

Ques 63 GATE 2012

A counter-current extraction column is designed to remove 99% of solute C from a solution of solvent A and solute C using pure solvent B. The initial concentration of solute in the solution of A + C is 20 wt %, and the total flow of solution is 1000 kg/h. If the equilibrium relationship is Y =2X , where Y= mass of C/mass of A and X= mass of C/mass of B.
If the flow rate of B is 2400 kg/h, then the theoretical number of stages in the column, using Kremser's equation (adjusted to the next integer) is

A

5

B

9

C

11

D

13


(b) is the correct answer.

Ques 64 GATE 2012

In a mixing tank operating at very high Reynolds number (>104), if the diameter of the impeller is doubled (other conditions remaining constant), the power required increases by a factor of

A

1/32

B

1/4

C

4

D

32


(d) is the correct answer.

Ques 65 GATE 2012

A batch reactor produces 1×105 kg of a product per year. The total batch time (in hours) of the reactor is k√PB, where PB is the product per batch in kg and k=1.0 h/√kg. The operating cost of the reactor is Rs. 400/h. The total annual fixed charges are Rs. 340×PB and the annual raw material cost is Rs. 2×106. The optimum size (in kg) of each batch (adjusted to the nearest integer) is

A

748

B

873

C

953

D

1148


(c) is the correct answer.

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