Chemical Engineering Gate Yearwise 


Chemical Engineering Gate 2014 Questions with Answer

Ques 40 GATE 2014

In a completely opaque medium, if 50% of the incident monochromatic radiation is absorbed, then which of the following statements are CORRECT?
P. 50% is reflected
Q. 50% is transmitted
R. 25% of the incident radiation is transmitted
S. 0% is transmitted

A

P and Q only

B

Q and R only

C

P and Q only

D

R and S only


(a) is the correct answer.

Ques 41 GATE 2014

A brick wall of 20 cm thickness has thermal conductivity of 0.7 W m-1K-1. An insulation of thermal conductivity 0.2 W m-1K-1 is to be applied on one side of the wall, so that the heat transfer through the wall is reduced by 75%. The same temperature difference is maintained across the wall before and after applying the insulation. The required thickness (in cm) of the insulation is


(17.14) is the correct answer.

Ques 42 GATE 2014

An oil with a flow rate of 1000 kg/h is to be cooled using water in a double-pipe counter-flow heat exchanger from a temperature of 70°C to 40°C. Water enters the exchanger at 25°C and leaves at 40°C. The specific heats of oil and water are 2 kJ kg-1K-1 and 4.2 kJ kg-1 K-1, overall heat transfer coefficient is 0.2 kW m-2K-1. The minimum heat exchanger area (in m2) required for this operation is


(3.85) is the correct answer.

Ques 43 GATE 2014

The bottom face of a horizontal slab of thickness 6 mm is maintained at 300°C. The top face is exposed to a flowing gas at 30°C. The thermal conductivity of the slab is 1.5 W m-1K-1 and the convective heat transfer coefficient is 30 W m-2K-1. At steady state, the temperature (in °C) of the top face is


(271) is the correct answer.

Ques 44 GATE 2014

Integral of the time-weighted absolute error (ITAE) is expressed as

A

∫0∞(|ε(t)|/t2)dt

B

∫0∞(|ε(t)|/t)dt

C

∫0∞t|ε(t)|dt

D

∫0∞t2|ε(t)|dt


(c) is the correct answer.

Ques 45 GATE 2014

A unit IMPULSE response of a first order system with time constant τ and steady state gain Kp is given by

A

1/(Kpτ)et/τ

B

Kpe-t/τ

C

τKpe-t/τ

D

(Kp/τ)e-t/τ


(d) is the correct answer.

Ques 46 GATE 2014

Assume that an ordinary mercury-in-glass thermometer follows first order dynamics with a time constant of 10 s. It is at a steady state temperature of 20°C. At t=0, the thermometer is suddenly immersed in a constant temperature bath of 95°C. The time (in s) for the thermometer to read 95°C, approximately is


(b) is the correct answer.

Ques 47 GATE 2014

A step change of magnitude 2 is introduced into a system having the following transfer function G(s)=2/(s2+2s+4). The percent overshoot is


(16.3) is the correct answer.

Ques 48 GATE 2014

Given below is a simplified block diagram of a feedforward control system.

The transfer function of the process is Gp=5/(s+1) and the disturbance Gd=1/(s2+2s+1). The transfer function of the PERFECT feedforward controller, Gf(s) is

A

-5/(s+1)3

B

-5/(s+1)

C

-1/(5(s+1))

D

- (s+1)/5


(c) is the correct answer.

Ques 49 GATE 2014

A process with Gp=2/(s-1) is to be controlled by a feedback proportional controller with a gain Kc. If the transfer functions of all other elements in the control loop are unity, then which ONE of the following conditions produces a stable closed loop response?

A

Kc=0.25

B

0<Kc<0.25

C

0.25<Kc<0.5

D

Kc>0.5


(d) is the correct answer.

Ques 50 GATE 2014

Consider the following block diagram for a closed-loop feedback control system

A proportional controller is being used with Kc=-4. If a step change in disturbance of magnitude 2 affects the system, then the value of the offset is


(0.5) is the correct answer.

Ques 51 GATE 2014

Two elemental gases (A and B) are reacting to form a liquid (C) in a steady state process as per the reaction A+B→C. The single-pass conversion of the reaction is only 20% and hence recycle is used. The product is separated completely in pure form. The fresh feed has 49 mol% of A and B each along with 2 mol% impurities. The maximum allowable impurities in the recycle stream is 20 mol%. The amount of purge stream (in moles) per 100 moles of the fresh feed is


(10.0) is the correct answer.

Ques 52 GATE 2014

Packed towers are preferred for gas-liquid mass transfer operations with foaming liquids because

A

in packed towers, high liquid to gas ratios are best handled

B

in packed towers, continuous contact of gas and liquid takes place

C

packed towers are packed with random packings

D

in packed towers, the gas is not bubbled through the liquid pool


(d) is the correct answer.

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