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# Multiple choice question for engineering

## Set 1

1. For a partial Condenser, the terms for middle diagonals are?
a) KIf and LiF
b) -(1+L1/KI1D)
c) -(Aij)
d) Aij

Answer: b [Reason:] For a partial Condenser the terms for middle diagonals -(1+L1/KI1D)=mi1 and Aij represents the factor of equilibrium.

2. For a partial Condenser, the terms for lower diagonals are?
a) -(1+L1/KI1D)
b) -(Aij)
c) L1/KI1D
d) Aij

Answer: c [Reason:] For a partial Condenser the terms for lower diagonals are L1/KI1D=Ai1 and L1/KI1D represents the equivalent to absorption factor.

3. For a reboiler stage N, the middle diagonal is
a) -(1+L1/KI1D)
b) KIf and LiF
c) L1/KI1D
d) -(1+B1/KI1VN)

Answer: d [Reason:] For a reboiler stage N the middle diagonal is-(1+B1/KI1VN), -(1+L1/KI1D) represents the next set of absorption factor of next + 1 stages.

4. For a total condenser, the reflux ratio just include
a) L1/KI1D
b) – (1+L1/D)
c) – (1+L1/KI1D)
d) – (Aij)

Answer: b [Reason:] For a total condenser the reflux ratio just include mij= – (1+L1/D), Where D is the distillate of the column and L is the liquid flow rate of column.

5. In matrix form, the total material balance equations are expressed as
a) F V=-R
b) RV=-F
c) L/V=F
d) V/R = F

Answer: b [Reason:] In matrix form the total material balance equations are expressed as RV= -F, this matrix can be solved either by determinant method or L U method.

6. In Thomas algorithm
a) Stage factor is calculated
b) Reflux factor is calculated
c) Feed factor is calculated
d) Boil up factor is calculated

Answer: a [Reason:] In Thomas algorithm Stage factor is calculated, in various other such as matrix method the reflux and the feed factor are to be calculated.

7. Forward elimination always starts from the
a) Right of corner
b) Middle of corner
c) Upper left corner
d) Last row

Answer: c [Reason:] Forward elimination always starts from the upper left corner, all elements are covered as the approach is from top to bottom.

8. Back substitution always starts from the
a) Lower right corner
b) Middle of corner
c) Upper right corner
d) Last row

Answer: a [Reason:] Back substitution always starts from the lower right corner and all elements are considered as the bottom to top approach method.

9. For Wide boiling mixtures, K value is
a) Different at different places
b) Same at different places
c) Specific at any time
d) Final Temperature based

Answer: a [Reason:] Wide boiling mixtures have K value is Different at different places, K value is independent of temperature, pressure and other affecting phenomena.

10. Each row acts as a
a) Different factor
b) Same factor
c) Coinciding factors
d) Elliptical Factor

Answer: a [Reason:] Each row acts as a Different factor, the pressure, temperature, volume all other factors are arranged in a separate column to differentiate between them.

## Set 2

1. The Wang Henke equation is used, for the calculation of
a) Flow rates
b) Volatility
c) Stages
d) Reflux

Answer: a [Reason:] The Wang Henke equation is used for the calculation of component and flow rates, Fenske’s for relative volatility and material balance for flow rates.

2. Wide boiling and energy coupled systems are drastically
a) Exponential
b) Linear
c) Logarithmic
d) Semi logical

Answer: b [Reason:] Wide boiling and energy coupled systems are drastically Linear, while d/b plots are nonlinear and equilibrium plots are also nonlinear.

3. Difference between k and k+1 should be very
a) Small
b) Large
c) Zero
d) Unity

Answer: a [Reason:] Difference between k and k+1 should be very small, if the difference increases this could cause problems like stage failure and flooding.

4. Rigorous method are based on?
a) Heat duties
b) Product compositions
c) Feed tares
d) Stages

Answer: a [Reason:] Rigorous method are based on Heat duties and other methods are based on the feed and Product compositions.

5. MESH equations are written in terms of?
a) Mass rates
b) Flow rates
c) Vapor rates
d) Liquid rate

Answer: c [Reason:] MESH equations are written in terms of Vapor rates and material balance equations are written in mass and flow rates.

6. In matrix form, system equation is expressed as
a) rivi = -fj
b) rivi = -Kj
c) rivi = -Gj
d) rivi = -Zj

Answer: a [Reason:] In matrix form system equation is expressed as rivi = -fj, where f is the function of the matrix and ri and vi are rows and columns.

7. The transposed vapor rate vector, Vi is raised to power of
a) Jk
b) Ik
c) T
d) P

Answer: c [Reason:] As Vi = (di, vi1, vi2, viN) T So T is Power, here T represents the temperature on which the vapor rate is measured.

8. The transposed feed Rate vector, is proportional to
a) T
b) G
c) K
d) P

Answer: a [Reason:] fj = (0, 0, 0……Vi…0, 0)T So T is Power of the function and the zero represents the empty states in the function.

9. The adiabatic split of vapor and liquid portion are expressed as
a) VIf and LiF
b) KIf and LiF
c) VIf and KiF
d) XIf and YiF

Answer: c [Reason:] The adiabatic split of vapor and liquid portion are expressed as VIf and LIf, These are equally important for all compositions of vapor and liquid.

10. The main diagonal mij is expressed as
a) –(1+Aij)
b) -(Aij)
c) 1-Aij
d) Aij

Answer: a [Reason:] Here mij=–(1+Aij) for any stage j, while -(Aij) represent only the factor for both gas and liquid phases and negative sign indicates the decreasing slope.

## Set 3

1. The difference between the value which has been computed and the correct value is?
a) Error
b) Shift
c) Dynamic
d) Static

Answer: a [Reason:] It is always an error, the deflection in original value from the calculate value is defined as error also can be calculated as percent of error.

2. Inside out method apply, Stripping factor to
b) Adjust Final Values
c) Adjust flow rates

Answer: c [Reason:] Inside out method apply Stripping factor to Adjust flow rates, while NR method applies to adjust the reflux.

3. Negative flow may be removed by increasing?
a) Feed
b) Reflux
c) Trays
d) Stages

Answer: b [Reason:] Negative flow may be removed by increasing Reflux, as the flow increase it causes the danger of flooding and thus increasing reflux is the only option.

4. A reversed temperature profile, means problem with
a) Column temperature
b) Stage temperature
c) Feed temperature
d) Plate temperature

Answer: c [Reason:] A reversed temperature profile means problem with feed temperature in vapor phase because vapor are intended to rise up and dissolve within liquid thus affecting liquid temperature.

5. Accuracy depends upon the?
a) H value
b) S value
c) T value
d) K value

Answer: d [Reason:] In rigorous calculation accuracy depends upon the K value, the ratio of the K values is the deciding factor of accuracy of i and j components.

6. Aij is the?
a) Absorption factor
b) Mass transfer area
c) Activity of i and j
d) Stripping Factor

Answer: a [Reason:] Aij is the Absorption factor for component i and stage j, while “a” denotes the mass transfer area and V/L is the stripping factor.

7. C is the?
a) Heat capacity
b) Coefficient
c) Total component
d) Final component

Answer: c [Reason:] C is the Total component or last components also Cp is called heat capacity measure in (KJ/Kg.K) Cp water is 4.328.

8. For the below graph the Pinch point is at? a) 5th stage
b) 9th stage
c) 10th stage
d) 2nd stage

Answer: a [Reason:] As seen in the graph Pinch point is at 5th stage, where the operating line and the equilibrium curve meets is called the pinch point.

9. Bubble point is at? a) A
b) B
c) C
d) Wrong interpretation

Answer: a [Reason:] A represents the bubble point at P-T Curve starting, as then temperature increases and approaches the dew point.

10. In the same diagram, Critical point is at?
a) A
b) B
c) C
d) Wrong interpretation

Answer: c [Reason:] C represents the bubble point at P-T curve where it is the Extreme point, the highest value reached and then the curve decreases to lowest temperature.

## Set 4

1. The 2N Newton method is based on algorithm of?
a) N X N
b) 2 X N
c) N X M
d) 2 X M

Answer: b [Reason:] The 2N Newton method is based on algorithm of 2 X N, while N X N is called as the Jacobin matrix.

2. XIJ and Yij are the component balances of
a) Equilibrium relation
b) Constant relation
c) Final relation
d) Direct relation

Answer: a [Reason:] XIJ and Yij are the component balances of Equilibrium relation, Whereas X=Y represents the final relation of the system.

3. Which method uses the summation of the equations for vapor and liquid components?
a) NR Method
b) RF Method
c) Tomich Method
d) 2N Method

Answer: d [Reason:] Tomich Method uses the summation of the equations for vapor and liquid components, while RF and NR are based on the initial conditions of column.

4. The independent variables of independent functions are used as, Fi =
a) [E1 E2 E3 …. EN-1 EN, K1 K2 K3 …. KN-1 KN].
b) [T1 T2 T3 …. TN-1 TN, K1 K2 K3 …. KN-1 KN].
c) [S1 S2 S3 …. SN-1 SN, E1 E2 E3 …. EN-1 EN].
d) [K1 K2 K3 …. KN-1 KN, T1 T2 T3 …. TN-1 TN].

Answer: c [Reason:] As Fi= [S1 S2 S3 …. SN-1 SN, E1 E2 E3 …. EN-1 EN] T , where S is the same factor as used in Fenske’s equation and E are the respective energy of the systems.

5. The stages flow rate and the vapor flow rates are expressed, as
a) [E1 E2 E3 …. EN-1 EN, V1 V2 K3 …. VN-1 VN].
b) [T1 T2 T3 …. TN-1 TN, V1 V2 V3 …. VN-1 VN].
c) [S1 S2 S3 …. SN-1 SN, E1 E2 E3 …. EN-1 EN].
d) [K1 K2 K3 …. KN-1 KN, T1 T2 T3 …. TN-1 TN].

Answer: b [Reason:] As Xi= [T1 T2 T3 …. TN-1 TN, V1 V2 V3 …. VN-1 VN] T, where T is defined as respective temperature and the volume V corresponding to the same relation.

6. The initial assumption to Tomich method is
a) Set initial Temperature
b) Set total stages
c) Final Pressure
d) Initial Pressure

Answer: a [Reason:] The initial assumption to Tomich method is to set initial Temperature for each stage, for any other method feed rates and total mole balance are assumed.

7. The θj factor is a
a) Subtracted
c) Multiplier
d) Divider

Answer: c [Reason:] As |L/V| = θj*|Lj/Vj|CR and θj factor is a Multiplier, this is based on a correlation that acts as a correction factor of the calculation.

8. Newton’s method is a fixed point iteration method, As Pn
a) g(Pn-1)
b) (Pn-1)
c) g
d) Pn

Answer: a [Reason:] Always Pn = g (Pn-1) is fixed point as in newton method, while other method NR and RS stage iterations are made as the problem proceeds.

9) Newton’s method cannot continue, if for some Pn-1
a) f’(Pn+1)
b) f’(P)
c) f’(Pn-1)
d) P

Answer: c [Reason:] Newton’s method cannot continue if for some f’ (Pn-1), as the derivative at some point becomes zero then this is called as failure in the newton’s method.

10. Given ε>0. Then
a) f(a)f(b)>0
b) f(a)f(b)=0
c) f(a)f(b)=1
d) f(a)f(b)<0

Answer: d [Reason:] Choose a and b so that f (a) f(b)< 0, if a and b are not given they are assumed to be as the average value of f(0) for two consecutive negative and positive outcomes.

## Set 5

1. The following equation represents? a) Net gain by Vapor
b) Total net gain
c) Net specific gain
d) Specific gain

Answer: a [Reason:] Net gain by Vapor is the product of initial vapor gain and the difference in the activity area daj thus giving us the net gain of vapor.

2. The following equation represents? a) Total net gain
b) Net gain by Liquid
c) Net specific gain
d) Specific gain

Answer: b [Reason:] Net gain by Liquid is the product of initial liquid gain and the difference in the activity area daj thus giving us the net gain of liquid also called equilibrium gain.

3. In the following equation, evj represents? a) Gas flux
b) Liquid flux
c) Energy
d) Equilibrium

Answer: a [Reason:] Gas flux at interfacial area daj and the equilibrium energy consumption based on the area of action and effective energy.

4. In the below equation, eLj represents? a) Gas flux
b) Equilibrium
c) Energy
d) Liquid flux

Answer: d [Reason:] Liquid flux at interfacial area daj, energy involved per unit area involved is defined as the liquid flux.

5. The below equation represents? a) Stages Number
b) Separation efficiency
c) Purity specification
d) Specific gain

Answer: c [Reason:] Purity specification, the ratio of quantities of the calculated to expect molar purity when subtracted from unity gives the specification of purity.

6. When this condition satisfies a) Mass transfer at interface should cancel
b) Mass transfer at interface should unite
c) Mass transfer at interface should maximum
d) Mass transfer at interface should minimum

Answer: a [Reason:] Mass transfer at interface should cancel, also defined as the difference between the liquid and gas quantities.

7. MERQ Stands for?
a) Material, equilibrium, regression and heat
b) Material, Energy, rate and equilibrium
c) Material, equilibrium, summation and Quality
d) Material, equilibrium, summation and heat

Answer: b [Reason:] MERQ Stands for Material, Energy, rate and equilibrium, Whereas MESH stands for Material, equilibrium, summation and heat.

8. How many trays are there per section of packing?
a) 2C+1
b) 3C+1
c) 4C+1
d) 5C+1

Answer: d [Reason:] There 5C+1 per section of packing, as there are C+1 stages in C equations, similar to that there exist 5C packs per section.

9. How many trays are there in complete column?
a) N (3C+1)
b) N (2C+1)
c) N (5C+1)
d) N (6C+1) 