## Interview MCQ Set 1

1. What is the third phase in all the two phase systems?

a) The adsorbent

b) The interface

c) The container

d) The atmosphere

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2. How to separate vapor-liquid-liquid system?

a) Fractional distillation

b) Fractional crystallization

c) Zone melting

d) Three phase isothermal flash

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3. Why are calculations for three phase flash difficult?

a) Because of strong dependency of K values on liquid phase composition when two immiscible liquids are present

b) Because of strong dependency of K values on vapor phase composition when two immiscible liquids are present

c) Because of strong dependency of K values on liquid phase composition when two miscible liquids are present

d) Because of strong dependency of K values on liquid phase composition when three immiscible liquids are present

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4. What is the enthalpy balance for three phase system?

a) h_{F}F + Q =h_{v}V + h_{L}L^{(1)} + hLL^{(2)}

b) h_{F}F =h_{v}V + h_{L}L^{(1)} + h_{L}LL^{(2)}

c) h_{F}F – Q =h_{v}V + h_{L}^{(1)} + h_{L}LL^{(2)}

d) h_{F}F + Q =h_{v}V + h_{L}L + h_{L}LL

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_{F}F + Q =h

_{v}V + h

_{L}L

^{(1)}+ hLL

^{(2)}.

5. The calculations of multiphase system are made by:

a) Graph

b) Hand calculations

c) Trial and error

d) Process simulators

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6. If at a certain pressure the vapor pressure of water is 4.74pisa and the mole fraction of water is 0.923, find out the crystallizer pressure.

a) 2.5pisa

b) 4.38pisa

c) 4.56pisa

d) 4.76pisa

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^{s}x

_{h20}. Hence P=4.74*0.923=4.38pisa.

7. If at a certain pressure the vapor pressure of water is 8pisa and the mole fraction of water is 0.9, find out the crystallizer pressure.

a) 0.64pisa

b) 7.2pisa

c) 0.66pisa

d) 0.81pisa

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^{s}x

_{h20}. Hence P=8*0.9=7.2pisa.

8. If at a certain pressure the vapor pressure of water is 6pisa and the mole fraction of water is 0.7, find out the crystallizer pressure.

a) 3.3pisa

b) 3.5pisa

c) 3.96pisa

d) 4.2pisa

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^{s}x

_{h20}. Hence P=6*0.7=4.2pisa.

9. If at a certain pressure the vapor pressure of water is 2pisa and the mole fraction of water is 0.9, find out the crystallizer pressure.

a) 0.45pisa

b) 1.8pisa

c) 3.6pisa

d) 0.81pisa

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^{s}x

_{h20}. Hence P=2*0.9=1.8pisa.

10. If at a certain pressure the vapor pressure of water is 10pisa and the mole fraction of water is 0.8, find out the crystallizer pressure.

a) 5pisa

b) 6pisa

c) 7pisa

d) 8pisa

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^{s}x

_{h20}. Hence P=10*0.8=8pisa.

## Interview MCQ Set 2

1. The Newton-Raphson method of finding roots of nonlinear equations falls under the category of which method?

a) Bracketing

b) Random

c) Open

d) Graphical

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2. What is the formula of finding the square root of R from equation x2- R=0?

a) X_{i+1}= 0.5(x_{i} + R/x_{i})

b) X_{i+1}= 0.5(x_{i} + R/2)

c) X_{i}= 0.5(x_{i} + R/x_{i})

d) X_{i}+1= 0.5(x_{i} + x_{i})

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^{2}– R=0 is X

_{i}+1= 0.5(x

_{i }+ R/x

_{i}).

3. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 1m and length 10m, what is the residence time?

a) 28s

b) 56s

c) 35s

d) 39s

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_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)10/500=56s.

4. If broth flow rate is 600kg/hr and solvent flow rate is 400kg/hr and POD is of diameter 1m and length 5m, what is the residence time?

a) 28s

b) 14s

c) 30s

d) 35s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)5/1000=14s.

5. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 1m and length 15m, what is the residence time?

a) 72s

b) 76s

c) 82s

d) 85s

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_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)15/500=85s.

6. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 2m and length 5m, what is the residence time?

a) 98s

b) 111ss

c) 113s

d) 119s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(4/4)5/500=113s.

7. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 1m and length 6m, what is the residence time?

a) 28s

b) 20s

c) 30s

d) 34s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)6/500=34s.

8. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 1m and length 7m, what is the residence time?

a) 28s

b) 20s

c) 40s

d) 35s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)7/500=40s.

9. If broth flow rate is 200kg/hr and solvent flow rate is 300kg/hr and POD is of diameter 3m and length 5m, what is the residence time?

a) 200s

b) 250s

c) 230s

d) 254s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(9/4)5/500=254s.

10. If broth flow rate is 200kg/hr and solvent flow rate is 500kg/hr and POD is of diameter 1m and length 5m, what is the residence time?

a) 28s

b) 20s

c) 30s

d) 35s

### View Answer

_{tme}= pi*(D

^{2}/4)L/F+S, t

_{time}= 3.14*(1/4)5/700=20s.

## Interview MCQ Set 3

1. What is the p-v-T equation of state?

a) Relationship between volume and temperature

b) Relationship between pressure, molar volume and temperature

c) Relationship between pressure and temperature

d) Relationship between pressure and molar volume

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2. What does the ideal gas equation neglects?

a) Temperature of molecules

b) Friction between molecules

c) Volume occupied by the molecules

d) Pressure occupied by the molecules

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3. What is the van der waal’s equation of non-ideal gas?

a) [P + a(n/v)^{2}](v/n –b) =RT

b) [P + a(n/v)^{2}] =RT

c) [P + (n/v)^{2}](v/n –b) =RT

d) [P + a(n/v)^{2}](v/n ) =RT

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^{2}](v/n –b) =RT is the correct equation for real gases.

4. What is the formula for acentric factor?

a) Z = (-log(P^{s}/P_{c})_{Tr=o.7}) – 1000

b) z = (-log(P^{s}/P_{c})_{Tr=o.7}) – 1.000

c) ω = (-log(P^{s}/)_{Tr=o.7}) – 1.000

d) ω = (-log(P^{s}/P_{c})_{Tr=o.7}) – 1.000

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^{s}/P

_{c})

_{Tr=o.7}) – 1.000 is the correct equation for determining acentric factor based on the law of corresponding states.

5. What is the value of ω for symmetric molecules?

a) 1

b) 0.264

c) 0

d) 0.490

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6. How can the compressibility factor be determined form generalized equation and Redich-kwong equation?

a) Z^{3} – Z^{2} + (A-B-B^{2})Z – AB =0

b) Z^{3} – Z^{2} + (A-B-B^{2}) – AB =0

c) Z^{3} – Z^{2} + (A-B-B^{2})Z – A =0

d) Z3 – Z2 + (A-B)Z – AB =0

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^{3}– Z

^{2}+ (A-B-B

^{2})Z – AB =0 where A and B are constants which can be determined.

7. If A =0.2724 and B= 0.05326 find the value of compressibility factor Z.

a) 0.7867

b) 0.7314

c) 0.8656

d) 10.435

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^{3}– Z

^{2}+ (A-B-B

^{2})Z – AB =0 is the equation used. Hence by solving Z

^{3}– Z

^{2}+ (0.2724-0.05326-0.05326

^{2})Z – 0.2724*0.05326 =0 we get Z= 0.7314.

8. What is the correct representation of Soave-Redich-Kwong equation?

a) P = [RT/v-b] – [a/v^{2}+bv+a].

b) P = [RT/v-b] – [a/v^{2}+bv].

c) P = [RT/v-b] – [a/v^{2}+bv+b].

d) P = [RT/v-b] – [a/v^{2}].

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^{2}+bv] is the Soave-Redich-Kwong equation.

9. What is the value of b if the temperature is 477.6K and the saturation pressure is 2829kPa?

a) 836.7 units

b) 2334.666 units

c) 0.0626 units

d) 0.4356 units

### View Answer

_{c}is the equation is used to determine b. Hence b= 0.08664 *8.314*477.6/2829000= 2334.666 units

10. If the critical temperature of propane is 369.8K and temperature of mixture is 477.6K and the saturation pressure is 4250kPa , what is the value of a?

a) 234.5 units

b) 678.9 units

c) 765.6 units

d) 836.7 units

### View Answer

^{2}T

_{c}

^{2.5}/P

_{c}T

^{0.5}is the equation used to calculate a. Hence a= 0.427(8.314)

^{2}(369.8)

^{2.5}/4250000*(477.6)

^{0.5}.

## Interview MCQ Set 4

1. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 20.2% is dried and brought to 20%.

a) 0.168

b) 0.234

c) 0.200

d) 0.300

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2. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 15 % is dried and brought to 14.8%.

a) 0.168

b) 0.130

c) 0.200

d) 0.300

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3. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 20.2% is dried and brought to 20%.

a) 0.168

b) 0.234

c) 0.156

d) 0.115

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4. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 18% is dried and brought to 17.8%.

a) 0.168

b) 0.146

c) 0.152

d) 0.234

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5. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 25% is dried and brought to 24.8%.

a) 0.16

b) 0.27

c) 0.200

d) 0.300

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6. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 20.2% is dried and brought to 20%.

a) 0.168

b) 0.234

c) 0.200

d) 0.237

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7. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 27% is dried and brought to 26.5%.

a) 0.324

b) 0.234

c) 0.225

d) 0.212

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8. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 20.2% is dried and brought to 20%.

a) 0.168

b) 0.259

c) 0.254

d) 0.257

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9. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 30% is dried and brought to 28%.

a) 0.168

b) 0.289

c) 0.276

d) 0.248

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10. Calculate the initial weight of moisture if one kg block of borax laundry soap with initial moisture content of 24% is dried and brought to 20%.

a) 0.194

b) 0.236

c) 0.876

d) 0.239

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## Interview MCQ Set 5

1. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.2295

Calculate the number of ideal countercurrent washing stages required.

a) 2.5

b) 2.6

c) 2.8

d) 2.95

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 2.95.

2. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.35

Calculate the number of ideal countercurrent washing stages required.

a) 2.5

b) 4.1

c) 2.2

d) 6.14

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 4.1.

3. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.1165

Calculate the number of ideal countercurrent washing stages required.

a) 2.0

b) 2.6

c) 2.8

d) 2.95

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 2.0.

4. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.55

Calculate the number of ideal countercurrent washing stages required.

a) 4.6

b) 6.4

c) 7.2

d) 2.95

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 7.2.

5. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.256

Calculate the number of ideal countercurrent washing stages required.

a) 3.18

b) 2.6

c) a)8

d) 3.67

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 3.18.

6. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.318

Calculate the number of ideal countercurrent washing stages required.

a) 2.5

b) 2.6

c) 3.8

d) 3.18

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 3.8.

7. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.108

Calculate the number of ideal countercurrent washing stages required.

a) 6.13

b) 2.45

c) 1.95

d) 2.95

### View Answer

_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 1.94.

8. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.44

Calculate the number of ideal countercurrent washing stages required.

a) 2.5

b) 5.3

c) 5.4

d) 5.5

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 5.3.

9. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.24

Calculate the number of ideal countercurrent washing stages required.

a) 3.0

b) 3.7

c) 2.8

d) 3.95

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_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 3.0.

10. If Y_{N+1}= 0.0005

X_{N}= 0.001

Y_{2}= 0.01174

Y_{L}=X_{L}= 0.05

L/V= 0.29

Calculate the number of ideal countercurrent washing stages required.

a) 3.5

b) 3.6

c) 3.8

d) 3.95

### View Answer

_{N}-Y

_{N+1}/Y

_{L}-Y

_{2})/log(L/V), hence N= 3.5.