GATE CH purpose:exam-prep PYQs & Answers — Page 18

Questions 171–180 of 650. Imported answers require independent review unless marked reviewed.

Sulfur dioxide (SO

) gas diffuses through a stagnant air-film of thickness 2 mm at 1 bar and 30 °C. The diffusion coefficient of SO

in air is

. The SO

partial pressures at the opposite sides of the film are 0.15 bar and 0.05 bar. The universal gas constant is 8.314 J mol

. Assume ideal gas behavior, the steady-state flux of SO

in mol m

through the air-film is

Your answerChoose one option.

0.077

0.022

0.085

0.057

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A simple distillation column separates a binary mixture of

and

. The relative volatility of

with respect to

is 2. The steady-state composition of

in the vapour leaving the 1

, 2

and 3

trays in the rectifying section are 94, 90 and 85 mol%, respectively. For ideal trays and constant molar overflow, the reflux-to-distillate ratio is

Your answerChoose one option.

1.9

2.7

1.2

1.1

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Alumina particles with an initial moisture content of 5 kg per kg dry solid are dried in a batch dryer. For the first two hours, the measured drying rate is constant at 2 kg m

. Thereafter, in the falling-rate period, the rate decreases linearly with the moisture content. The equilibrium moisture content is 0.05 kg per kg dry solid and the drying area of the particles is 0.5 m

per kg dry solid. The total drying time, in h, to reduce the moisture content to half its initial value is

Your answerChoose one option.

4.13

2.55

3.22

5.13

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A first-order heterogeneous reaction

is carried out using a porous spherical catalyst. Assume isothermal conditions, and that intraphase diffusion controls the reaction rate. At a bulk

concentration of 0.3 mol L

, the observed reaction rate in a 3 mm diameter catalyst particle is 0.2 mol s

catalyst volume. At a bulk

concentration of 0.1 mol L

, the observed reaction rate, in mol s

catalyst volume, in a 6 mm diameter catalyst particle, is

Your answerChoose one option.

0.011

0.033

0.022

0.005

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A first-order liquid phase reaction

is carried out in two isothermal plug flow reactors (PFRs) of volume 1 m

each, connected in series. The feed flow rate and concentration of

to the first reactor are 10 m

and 1 kmol m

, respectively. At steady-state, the concentration of

at the exit of the second reactor is 0.2 kmol m

. If the two PFRs are replaced by two equal-volume continuously stirred tank reactors (CSTRs) to achieve the same overall steady-state conversion, the volume of each CSTR, in m

, is

Your answerChoose one option.

1.54

3.84

7.28

1.98

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The residence time distribution,

, for a non-ideal flow reactor is given in the figure. A first-order liquid phase reaction with a rate constant 0.2 min

is carried out in the reactor. For an inlet reactant concentration of 2 mol L

, the reactant concentration (in mol L

) in the exit stream is

Diagram for Chemical Engineering question 46

Your answerChoose one option.

0.905

0.452

1.902

0.502

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Let

and

be the polar coordinates defined by

and

. The area of the cardioid

, is

Diagram for Chemical Engineering question 47

Your answerChoose one option.

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For the block diagram shown in the figure, the correct expression for the transfer function

Diagram for Chemical Engineering question 48

Your answerChoose one option.

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For purchasing a batch reactor, three alternatives P, Q and R have emerged, as summarized in the table. For a compound interest rate of 10% per annum, choose the correct option that arranges the alternatives, in order, from the least expensive to the most expensive.

	P	Q	R
Installed Cost (lakh rupees)	15	25	35
Equipment Life (years)	3	5	7
Maintenance Cost (lakh rupees per year)	4	3	2

Your answerChoose one option.

P, Q, R

R, P, Q

R, Q, P

Q, R, P

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The Newton-Raphson method is used to solve

, where

. If the initial guess

, the value of the next iterate,

, rounded off to 2 decimal places, is ______

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GATE CH purpose:exam-prep PYQs

Question 41

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