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## Interview MCQ Set 1

1. How many fluids remain at constant temperature during the process of boiling and condensation?
a) 1
b) 2
c) 3
d) 4

Answer: a [Reason:] During the process of boiling and condensation, only a phase change takes place and one fluid remain at constant temperature.

2. Identify the correct expression for effectiveness
a) 4 – exponential (- NTU)
b) 3 – exponential (- NTU)
c) 2 – exponential (- NTU)
d) 1 – exponential (- NTU)

Answer: d [Reason:] Here, C MAX = infinity and C MIN/C MAX = 0.

3. In a gas turbine recuperator, the capacity ratio becomes
a) 2
b) 1
c) 4
d) 3

Answer: b [Reason:] In a gas turbine recuperator, the exhaust gases after expansion in the turbine are used to heat the compressed air.

4. In a gas turbine recuperator, the expression for effectiveness for the parallel flow configuration reduces to
a) 1 – exponential (- NTU)/3
b) 1 – exponential (- NTU)/4
c) 1 – exponential (- 2 NTU)/2
d) 1 – exponential (- NTU)/6

Answer: c [Reason:] In a gas turbine recuperator, the exhaust gases after expansion in the turbine are used to heat the compressed air.

5. What is the maximum efficiency for parallel flow heat exchanger?
a) 5%
b) 10%
c) 20%
d) 50%

Answer: a [Reason:] No matter how large the exchanger be or how high be the flow of overflow at transfer coefficient, the maximum efficiency for parallel flow heat exchanger is 5%.

6. A two pass surface condenser is required to handle the exhaust from a turbine developing 15 MW with specific steam consumption of 5 kg/k W h. The quality of exhaust steam is 0.9, the condenser vacuum is 66 cm of mercury while the bar meter reads 76 cm of mercury. The condenser tubes are 28 mm inside diameter, 4 mm thick and water flows through tubes with a speed of 3 m/s and inlet temperature 20 degree Celsius. All the steam is condensed, the condensate is saturated water and temperature of cooling water at exit is 5 degree Celsius less than the condensate temperature. Assuming that overall coefficient of heat transfer is 4 k W/m2 degree, determine the mass of cooling water circulated

a) 746.13 kg/s
b) 646.13 kg/s
c) 546.13 kg/s
d) 446.13 kg/s

Answer: d [Reason:] P S = 76 – 66/76 (1.0133) = 0.133 bar. From energy balance, heat loss by steam = heat gained by cooling water.

7. The curve of effectiveness versus NTU parameters indicates the relationship between
(i) Effectiveness
(ii) NTU MAX
(iii) C MIN/C MAX
Identify the correct statements
a) 1 and 2
b) 1, 2 and 3
c) 2 only
d) 3 only

Answer: b [Reason:] When any two of three parameters are known, the third can be find out.

8. Hot water having specific heat 4200 J/kg K flows through a heat exchanger at the rate of 4 kg/min with an inlet temperature of 100 degree Celsius. A cold fluid having a specific heat 2400 J/kg K flows in at a rate of 8 kg/min and with inlet temperature 20 degree Celsius. Make calculations for maximum possible effectiveness if the fluid flow conforms to parallel flow arrangement
a) 0.533
b) 0.633
c) 0.733
d) 1

Answer: a [Reason:] Maximum possible effectiveness = 1 – exponential (- infinity)/1 + C = 0.533.

9. Consider the above problem, make calculations for maximum possible effectiveness if the fluid flow conforms to counter flow arrangement
a) 1.23
b) 0.5
c) 1
d) 0.465

Answer: c [Reason:] Maximum possible effectiveness = 1 – exponential (- infinity)/ 1 – C exponential (- infinity) = 1.

10. A counter flow heat exchanger is used to col 2000 kg/hr of oil (c p = 2.5 k J/kg K) from 105 degree Celsius to 30 degree Celsius by the use of water entering at 15 degree Celsius. If the overall heat transfer coefficient is expected to be 1.5 k W/m2 K, find out the water flow rate. Presume that the exit temperature of the water is not to exceed 80 degree Celsius
a) 1680.2 kg/hr
b) 1580.2 kg/hr
c) 1480.2 kg/hr
d) 1380.2 kg/hr

Answer: d [Reason:] Mass flow rate of coolant = 2000 (2.5) (105-30)/4.18 (80-15) = 1380.2 kg/hr.

## Interview MCQ Set 2

1. In CI engine, combustion occurs by the high temperature produced by the compression of the air.
a) True
b) False

2. In the CI engine, the intake is air alone and the fuel is injected at high pressure in the form of fine droplets at the start of compression.
a) True
b) False

Answer: b [Reason:] No, but actually, in the CI engine, the intake is air alone and the fuel is injected at high pressure in the form of fine droplets near the end of compression.

3. The phases of CI engine combustion are
a) ignition delay period
b) period of rapid combustion
c) period of controlled combustion
d) all of the mentioned

Answer: d [Reason:] The three phases of CI engine combustion are a) ignition delay period b) period of rapid combustion c) period of controlled combustion.

4. The rate of pressure rise depends on the amount of fuel present at the end of delay period, degree of turbulence, fineness of atomization and spray pattern.
a) True
b) False

5. The factors affecting combustion in CI engine are
a) ignition quantity of fuel
b) injection pressure of droplet size
d) all of the mentioned

Answer: a [Reason:] The factors affecting combustion in CI engine are 1) ignition quantity of fuel 2) injection pressure of droplet size 3) injection advance angle 4) compression ratio 5) intake temperature 6) jacket water temperature 7) intake pressure 8) engine speed 9) load and air to fuel ratio 10) engine size 11) type of combustion chamber.

6. The factors affecting combustion in CI engine are
a) compression ratio
b) intake temperature
c) jacket water temperature
d) all of the mentioned

Answer: a [Reason:] The factors affecting combustion in CI engine are 1) ignition quantity of fuel 2) injection pressure of droplet size 3) injection advance angle 4) compression ratio 5) intake temperature 6) jacket water temperature 7) intake pressure 8) engine speed 9) load and air to fuel ratio 10) engine size 11) type of combustion chamber.

7. The factors affecting combustion in CI engine are
a) intake pressure
b) engine speed
c) load and air to fuel ratio
d) all of the mentioned

Answer: a [Reason:] The factors affecting combustion in CI engine are 1) ignition quantity of fuel 2) injection pressure of droplet size 3) injection advance angle 4) compression ratio 5) intake temperature 6) jacket water temperature 7) intake pressure 8) engine speed 9) load and air to fuel ratio 10) engine size 11) type of combustion chamber.

8. Towards the end of the compression stroke when injection of the fuel into the combustion chamber commences, the quantity of fuel discharged is spread out over a predetermined period.
a) True
b) False

9. The rate of burning does not depends on the relative movement of the burning droplets to the surrounding air charge.
a) True
b) False

Answer: b [Reason:] In fact, the rate of burning depends on the relative movement of the burning droplets to the surrounding air charge.

10. In CI engines fuel is injected into the combustion chamber at about 15ºC ___________ TDC during compression stroke.
a) after
b) before
c) at
d) none of the mentioned

## Interview MCQ Set 3

1. The coefficients of the polynomials P (S) and Q (S) in the network function N (S) are ________ for passive network.
a) real and positive
b) real and negative
c) complex and positive
d) complex and negative

Answer: a [Reason:] The coefficients of the polynomials P (S) and Q (S) in the network function N (S) are real and positive for passive network. On factorising the network function we obtain the poles and zeros.

2. The scale factor is denoted by the letter?
a) G
b) H
c) I
d) J

Answer: b [Reason:] The scale factor is denoted by the letter ‘H’ and its value is equal to the ratio of ao to bo.

3. The zeros in the transfer function are denoted by?
a) 3
b) 2
c) 1
d) 0

Answer: d [Reason:] The roots of the equation P (S) = 0 are zeros of the transfer function. The zeros in the transfer function are denoted by ‘o’.

4. The poles in the transfer function are denoted by?
a) x
b) y
c) z
d) w

Answer: a [Reason:] The roots of the equation Q (S) = 0 are poles of the transfer function. The poles in the transfer function are denoted by ‘x’.

5. The network function N (S) becomes _________ when s is equal to anyone of the zeros.
a) 1
b) 2
c) 0
d) ∞

Answer: c [Reason:] The network function N (S) becomes zero when s in the transfer function is equal to anyone of the zeros as the network function is completely defined by its poles and zeros.

6. The N (S) becomes ________ when s is equal to any of the poles.
a) ∞
b) 0
c) 1
d) 2

Answer: a [Reason:] The network function is completely defined by its poles and zeros and the network function N (S) becomes infinite when s in the transfer function is equal to anyone of the poles.

7. If the poles or zeros are not repeated, then the function is said to be having __________ poles or ________ zeros.
a) simple, multiple
b) multiple, simple
c) simple, simple
d) multiple, multiple

Answer: c [Reason:] If the poles or zeros are not repeated, then the function is said to be having simple poles or simple zeros and the network function is said to be stable when the real parts of the poles and zeros are negative.

8. If the poles or zeros are repeated, then the function is said to be having __________ poles or ________ zeros.
a) multiple, multiple
b) simple, simple
c) multiple, simple
d) simple, multiple

Answer: a [Reason:] If there are repeated poles or zeros, then function is said to be having multiple poles or multiple zeros and the network function is stable if the poles and zeros lie within the left half of the s-plane.

9. If the number of zeros (n) are greater than the number of poles (m), then there will be _________ number of zeros at s = ∞.
a) n
b) m
c) n-m
d) n+m

Answer: c [Reason:] If the number of zeros (n) are greater than the number of poles (m), then there will be (n-m) number of zeros at s = ∞ and to obtain (n-m) zeros at s = ∞ the condition is n>m.

10. If the number of poles (m)are greater than the number of zeros (n), then there will be _________ number of zeros at s = ∞.
a) m+n
b) m-n
c) m
d) n

Answer: b [Reason:] If the number of poles (m)are greater than the number of zeros (n), then there will be (m-n) number of zeros at s = ∞ and to obtain (m-n) poles at s = ∞ the condition is m>n.

## Interview MCQ Set 4

1. How many computation rounds does the simplified AES consists of?
a) 5
b) 2
c) 8
d) 10

Answer: b [Reason:] The simplified AES has only 2 rounds of computation.

2. For the case of Mixed Columns and Inverse Mixed Columns, is it true that b(x) = a-1(x)mod(x4 + 1)
where a(x) = {03}x3 + {01}x2 + {01}x + {02} and b(x) = {0B}x3 + {0D}x2 + {09}x + {0E}
a) True
b) False. The expression for a(x) is wrong.
c) False. The expression for b(x) is wrong.
d) False. Both a(x) and b(x) are faulty.

Answer: a [Reason:] The statment is true and can be checked as it is similar to the matrix forms of mixed columns and inverse mixed columns.

3. For an inputs key of size 128 bits constituting of all zeros, what is w(7) ?
a) {62 63 63 63}
b) {62 62 62 62}
c) {00 00 00 00}
d) {63 63 63 62}

Answer: a [Reason:] Applying the key algorithm we get, w(0) = {00 00 00 00}; w(1) = {00 00 00 00}; w(2) = {00 00 00 00}; w(3) = {00 00 00 00}; w(4) = {62 63 63 63}; w(5) = {62 63 63 63}; w(6) = {62 63 63 63}; w(7) = {62 63 63 63}.

4. On comparing AES with DES, which of the following functions from DES does not have an equivalent AES function?
a) f function
b) permutation p
c) swapping of halves
d) xor of subkey with function f

Answer: c [Reason:] There is no equivalent to swapping of halves in the AES algorithm.

5. On perform the Mix Columns transformation for the sequence of bytes “77 89 AB CD” we get output
a) {01 55 EE 4A}
b) {0A 44 EF 4A}
c) {08 55 FF 3A}
d) {09 44 DD 4A}

Answer: c [Reason:] Perform the mix columns transformation to obtain the output {08 55 FF 3A}.

6.On perform the Mix Columns transformation for the sequence of bytes “67 89 AB CD” we get output
a) {08 55 FF 18}
b) {28 45 EF 08}
c) {28 45 FF 18}
d) {25 35 EF 08}

Answer: b [Reason:] Perform the mix columns transformation to obtain the output {28 45 EF 0A}.

7. Is the following matrix the inverse matrix of the matrix used in the mix columns step?
x3 + 1 x
x x3 + 1

a) Yes
b) No
c) Can’t say
d) Insufficient Information

Answer: a [Reason:] On multiplying this matrix with the mix columns matrix we get the identity matrix, this proves that it is an inverse matrix.

8. For the cipher text 0000 0111 0011 1000 and Key 0110 1111 0110 1011, apply the Simplified AES to obtain the plaintext. The plain text is
a) 0110 1001 0111 0001
b) 0110 1111 0110 1011
c) 0010 1001 0110 1011
d) 1111 0101 0111 1111

Answer: b [Reason:] On applying the simplified AES we would obtain 0110 1111 0110 1011 as the plain text.

9. What is the block size in the Simplified AES algorithm?
a) 8 bits
b) 40 bits
c) 16 bits
d) 36 bits

Answer: b [Reason:] The block size for the AES algorithm is 16 bits.

10. What is the key size in the S-AES algorithm?
a) 16 bits
b) 32 bits
c) 24 bits
d) None of the mentioned

Answer: a [Reason:] The key size in the S-AES algorithm is 16 bits.

11. S-AES and S-DES were both developed by the same person as an educational cryptography system to teach students
a) True
b) False

12. Which of the following is a faulty S-AES step function?
b) Byte substitution
c) Shift rows
d) Mix Columns

Answer: b [Reason:] The correct version in S-AES would be nibble substitution as 4 bits are taken at a time.

## Interview MCQ Set 5

1. What is the thermal conductivity of asphalt in W/m K?
a) 0.064
b) 0.063
c) 0.062
d) 0.061

Answer: c [Reason:] Asphalt concrete have three main structural elements i.e. aggregates, binder and the contact layer between them. It is soft at high temperatures but brittle at low temperatures.

2. Which one is having highest thermal conductivity?
a) Silver
b) Copper
c) Glass
d) Earth

Answer: a [Reason:] Thermal conductivity of silver is 410 W/m degree while that of copper, glass and earth are 385 W/m degree, 0.75 W/m degree and 0.138 respectively.

3. What is the thermal conductivity of magnetite in W/m K?
a) 3.7
b) 3.8
c) 3.9
d) 4.0

Answer: b [Reason:] This is having low thermal conductivity because of high intramolecular interactions between their outer edge molecules.

4. Which one is having lowest thermal conductivity?
a) Furnace
b) Wool
c) Saw dust
d) Glass wool

Answer: d [Reason:] Thermal conductivity of glass wool is 0.03 W/m degree while that of furnace, wool and saw dust are 0.30 W/m degree, 0.052 W/m degree and 0.07 respectively.

5. What is the thermal conductivity of coal in W/m K?
a) 0.25
b) 0.26
c) 0.27
d) 0.28

Answer: b [Reason:] Coal is composed primarily of carbon along with variable quantities of other elements such as hydrogen, sulfur, oxygen and nitrogen.

6. What is the thermal conductivity of cotton in W/m K?
a) 0.03
b) 0.04
c) 0.05
d) 0.06

Answer: d [Reason:] It is a soft material that grows in protective capsule, around the seeds of cotton plants.

7. Which one is having highest thermal conductivity?
a) Brass
b) Aluminum
c) Cast iron
d) Steel

Answer: b [Reason:] Thermal conductivity of aluminum is 225 W/m degree while that of brass, cast iron and steel are 107 W/m degree, 55 W/m degree and 20 respectively.

8. What is the thermal conductivity of apple in W/m K?
a) 0.513
b) 0.613
c) 0.713
d) 0.813

Answer: a [Reason:] It is a sweet fruit that has very low thermal conductivity in order to prevent it from damage.

9. What is the thermal conductivity of ice in W/m K?
a) 1.55
b) 1.66
c) 1.77
d) 1.88