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Chemical Engineering Gate 2021 Questions with Answer

Ques 53 GATE 2021

A process has a transfer function G(s)=Y(s)/X(s)=(20)/(9000s2+240s+1). Initially the process is at steady state with x(t=0)=0.4 and y(t=0)=100. If a step change in x is given from 0.4 to 0. 5, the maximum value of y that will be observed before it reaches the new steady state is _______ (round off to 1 decimal place).


(102.5) is the correct answer.

Ques 54 GATE 2021

In reverse osmosis, the hydraulic pressure and osmotic pressure at the feed side of the membrane are P1 and π1, respectively. The corresponding values are P2 and π2 at the permeate side. The membrane, feed, and permeate are at the same temperature. For equilibrium to prevail, the general criterion that should be satisfied is

A

π1=π2

B

P1=P2

C

P1+π1=P2+π2

D

P1-π1=P2-π2


(d) is the correct answer.

Ques 55 GATE 2021

Feed solution F is contacted with solvent B in an extraction process. Carrier liquid in the feed is A and the solute is C. The ternary diagram depicting a single ideal stage extraction is given below. The dashed lines represent the tie-lines.
The CORRECT option(s) is/are

A

For the tie-lines shown, concentration of solute in the extract is higher than that in the raffinate

B

Maximum amount of solvent is required if the mixture composition is at W

C

Y represents the composition of extract when minimum amount of solvent is used

D

U represents the raffinate composition if the mixture composition is at M


(a;c;d) is the correct answer.

Ques 56 GATE 2021

In a solvent regeneration process, a gas is used to strip a solute from a liquid in a countercurrent packed tower operating under isothermal condition. Pure gas is used in this stripping operation. All solutions are dilute and Henry's law, y*=mx is applicable. Here, y* is the mole fraction of the solute in the gas phase in equilibrium with the liquid phase of solute mole fraction x, and m is the Henry's law constant.
Let x1 be the mole fraction of the solute in the leaving liquid, and x2 be the mole fraction of solute in the entering liquid.
When the value of the ratio of the liquid-to-gas molar flow rates is equal to m, the overall liquid phase Number of Transfer Units, NTUOL, is given by

A

(x2-x1)/x1

B

(x2+x1)/(x2-x1)

C

ln(x2/x1)

D

ln((x2+x1)/(x2-x1))


(a) is the correct answer.

Ques 57 GATE 2021

A double-effect evaporator is used to concentrate a solution. Steam is sent to the first effect at 110°C and the boiling point of the solution in the second effect is 63.3°C. The overall heat transfer coefficient in the first effect and second effect are 2000 W m-2K-1 and 1500 W m-2K-1, respectively. The heat required to raise the temperature of the feed to the boiling point can be neglected. The heat flux in the two evaporators can be assumed to be equal.
The temperature at which the solution boils in the first effect is _______ °C (round off to nearest integer).


(90) is the correct answer.

Ques 58 GATE 2021

A distillation column handling a binary mixture of A and B is operating at total reflux. It has two ideal stages including the reboiler. The mole fraction of the more volatile component in the residue (xW) is 0.1. The average relative volatility αAB is 4. The mole fraction of A in the distillate (xD) is _______ (round off to 2 decimal places).


(0.64) is the correct answer.

Ques 59 GATE 2021

In a batch drying experiment, a solid with a critical moisture content of 0.2 kg H2O/kg dry solid is dried from an initial moisture content of 0.35 kg H2O/kg dry solid to a final moisture content of 0.1 kg H2O/kg dry solid in 5 h. In the constant rate regime, the rate of drying is 2 kg H2O/(m2.h). The entire falling rate regime is assumed to be uniformly linear. The equilibrium moisture content is assumed to be zero.
The mass of the dry solid per unit area is _______ kg/m2 (round off to nearest integer).


(35) is the correct answer.

Ques 60 GATE 2021

As shown in the figure below, air flows in parallel to a freshly painted solid surface of width 10 m, along the z-direction

The equilibrium vapor concentration of the volatile component A in the paint, at the air-paint interface, is CA,i. The concentration CA decreases linearly from this value to zero along the y-direction over a distance δ of 0.1 m in the air phase. Over this distance, the average velocity of the air stream is 0.033 m s-1 and its velocity profile (in m s-1) is given by vz(y)=10y2 where y is in meter.
Let CA,m represent the flow averaged concentration. The ratio of CA,m to CA,i, is _______ (round off to 2 decimal places).


(0.25) is the correct answer.

Ques 61 GATE 2021

Turnover ratio is defined as

A

Fixed capital investment/Gross annual sales

B

Gross annual sales/Fixed capital investment

C

Fixed capital investment/Average selling price of the product

D

Gross annual sales/Average selling price of the product


(b) is the correct answer.

Ques 62 GATE 2021

A principal amount is charged a nominal annual interest rate of 10%. If the interest rate is compounded continuously, the final amount at the end of one year would be

A

higher than the amount obtained when the interest rate is compounded monthly

B

lower than the amount obtained when the interest rate is compounded annually

C

equal to 1.365 times the principal amount

D

equal to the amount obtained when using an effective interest rate of 27.18%


(a) is the correct answer.

Ques 63 GATE 2021

A company invests in a recovery unit to separate valuable metals from effluent streams. The total initial capital investment of this unit is Rs. 10 lakhs.
The recovered metals are worth Rs. 4 lakhs per year.
If the annual return on this investment is 15%, the annual operating costs should be _______ lakhs of rupees (correct to 1 decimal place).


(2.5) is the correct answer.

Ques 64 GATE 2021

Operating labor requirements L in the chemical process industry is described in terms of the plant capacity C (kg day-1) over a wide range (103-106) by a power law relationship L=αCβ where α and β are constants. It is known that
L is 60 when C is 2×104
L is 70 when C is 6×104
The value of L when C is 105 kg day-1 is _______ (round off to nearest integer).


(75) is the correct answer.

Ques 65 GATE 2021

A viscous liquid is pumped through a pipe network in a chemical plant. The annual pumping cost per unit length of pipe is given by Cpump=(48.13 q2μ)/D4. The annual cost of the installed piping system per unit length of pipe is given by Cpiping=45.92D. Here, D is the inner diameter of the pipe in meter, q is the volumetric flowrate of the liquid in m3s-1 and μ is the viscosity of the liquid in Pa.s.
If the viscosity of the liquid is 20×10-3 Pa.s and the volumetric flow rate of the liquid is 10-4 m3s-1, the economic inner diameter of the pipe is _______ meter (round off to 3 decimal places).


(0.015) is the correct answer.

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