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Multiple choice question for engineering

Set 1

1. A mixture contains 20% of A with Heat Capacity 10 J/oC and 80% of B with Heat Capacity 5 J/oC, what is the Heat Capacity of mixture?
a) 6 J/oC
b) 7 J/oC
c) 8 J/oC
d) 9 J/oC

View Answer

Answer: a [Reason:] Heat capacity of mixture = 0.2*10 + 0.8*5 = 2 + 4 = 6 J/oC.

2. A mixture contains 40% of A with Heat Capacity 15 J/oC and 60% of B with Heat Capacity 10 J/oC, what is the Heat Capacity of mixture?
a) 11 J/oC
b) 12 J/oC
c) 13 J/oC
d) 14 J/oC

View Answer

Answer: b [Reason:] Heat capacity of mixture = 0.4*15 + 0.6*10 = 6 + 6 = 12 J/oC.

3. A mixture contains 50% of A with Heat Capacity 10 J/oC and 50% of B with Heat Capacity 20 J/oC, what is the Heat Capacity of mixture?
a) 12 J/oC
b) 15 J/oC
c) 17 J/oC
d) 18 J/oC

View Answer

Answer: b [Reason:] Heat capacity of mixture = 0.5*10 + 0.5*20 = 15 J/oC.

4. A mixture contains 20% of A with Heat Capacity 25 J/oC, 30% of B with Heat Capacity 20 J/oC, and 50% of C with Heat Capacity 10 J/oC, what is the Heat Capacity of mixture?
a) 10 J/oC
b) 14 J/oC
c) 16 J/oC
d) 20 J/oC

View Answer

Answer: c [Reason:] Heat capacity of mixture = 0.2*25 + 0.3*20 + 0.5*10 = 16 J/oC.

5. A mixture contains 30% of A with Heat Capacity 10 J/oC, 30% of B with Heat Capacity 20 J/oC, and 40% of C with Heat Capacity 35 J/oC, what is the Heat Capacity of mixture?
a) 14 J/oC
b) 17 J/oC
c) 19 J/oC
d) 23 J/oC

View Answer

Answer: d [Reason:] Heat capacity of mixture = 0.3*10 + 0.3*20 + 0.4*35 = 23 J/oC.

6. What is the enthalpy of a mixture having 10% of A with enthalpy 10 J, and 90% of B with enthalpy 20 J?
a) 10 J
b) 15 J
c) 18 J
d) 19 J

View Answer

Answer: d [Reason:] Heat capacity of mixture = 0.1*10 + 0.9*20 = 19 J.

7. What is the enthalpy of a mixture having 20% of A with enthalpy 15 J, and 80% of B with enthalpy 25 J?
a) 17 J
b) 19 J
c) 23 J
d) 28 J

View Answer

Answer: c [Reason:] Heat capacity of mixture = 0.2*15 + 0.8*25 = 23 J.

8. What is the enthalpy of a mixture having 40% of A with enthalpy 50 J, and 60% of B with enthalpy 25 J?
a) 30 J
b) 35 J
c) 40 J
d) 45 J

View Answer

Answer: b [Reason:] Heat capacity of mixture = 0.4*50 + 0.6*25 = 35 J.

9. What is the enthalpy of a mixture having 20% of A with enthalpy 20 J, 30% of B with enthalpy 40 J, and 50% of C with enthalpy 20 J?
a) 26 J
b) 29 J
c) 31 J
d) 34 J

View Answer

Answer: a [Reason:] Heat capacity of mixture = 0.2*20 + 0.3*40 + 0.5*20 = 26 J.

10. What is the enthalpy of a mixture having 10% of A with enthalpy 10 J, 30% of B with enthalpy 30 J, and 60% of C with enthalpy 25 J?
a) 21 J
b) 25 J
c) 27 J
d) 28 J

View Answer

Answer: b [Reason:] Heat capacity of mixture = 0.1*10 + 0.3*30 + 0.6*25 = 1 + 9 + 15 = 25 J.

11. What is the enthalpy change of solution if the enthalpy change of solute is 10 J, and enthalpy of solvent is 15 J?
a) 10 J
b) 15 J
c) 25 J
d) 40 J

View Answer

Answer: c [Reason:] ∆Hsolution = ∆Hsolute +∆Hsolvent = 10 + 15 = 25 J.

12. What is the enthalpy change of 8 mole solution if the enthalpy change of 5 mole solute is 10 J/mole, and enthalpy of 2 mole solvent is 15 J/mole?
a) 10 J/mole
b) 12 J/mole
c) 13 J/mole
d) 15 J/mole

View Answer

Answer: a [Reason:] ∆Hsolution = ∆Hsolute +∆Hsolvent, => ∆Hsolution = (10*5 + 15*2)/8 = 10 J/mole.

13. What is the heat evolved when a gaseous solute is mixed with liquid solvent?
a) Heat of solution
b) Heat of mixing
c) Heat of dissolution
d) All of the mentioned

View Answer

Answer: a [Reason:] When Gas is mixed with liquid the heat evolved is called heat of solution.

14. What is the heat evolved when a liquid solute is mixed with liquid solvent?
a) Heat of solution
b) Heat of mixing
c) Heat of dissolution
d) All of the mentioned

View Answer

Answer: b [Reason:] When liquid is mixed with liquid the heat evolved is called heat of mixing.

15. Heat of solution of a mixture is 10 J, what is the heat dissolution?
a) -10 J
b) 10 J
c) 0
d) Cannot be determined

View Answer

Answer: a [Reason:] Heat of dissolution = – Heat of solution = -10 J.

Set 2

1. _________ jets produce micro gas turbines.
a) Bladon
b) Turbo
c) Bladon & Turbo
d) None of the mentioned

View Answer

Answer: a [Reason:] Bladon jets produce micro gas turbines. Due to the weight to size constraint these are used.

2. Hybrid electric vehicles are powered by _________
a) turbo shafts
b) micro gas turbines
c) turbo jets
d) none of the mentioned

View Answer

Answer: b [Reason:] Hybrid electric vehicles are powered by micro gas turbines. Micro gas turbines are used by considering weight to size ratio.

3. Micro turbines are based on _________
a) weight
b) size
c) micro combustion
d) none of the mentioned

View Answer

Answer: c [Reason:] Micro combustion is the basic principle micro turbines are based upon.

4. In micro turbines generator is integrated with _________
a) turbine shaft
b) combustor
c) turbine shaft & combustor
d) none of the mentioned

View Answer

Answer: a [Reason:] In micro turbines generator is integrated with turbine shaft.

5. Micro turbines have ________ power to weight ratio.
a) constant
b) low
c) high
d) none of the mentioned

View Answer

Answer: c [Reason:] Micro turbines have high power to weight ratio. As weight of the micro gas turbines is less it automatically increases the ratio.

6. Micro turbines have ________ emissions.
a) high
b) low
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Micro turbines have low emissions. As power to weight ratio is less for micro turbines emissions are also reduced in micro gas turbines.

7. Micro turbines are more efficient at ________ power level when compared to reciprocating engines.
a) high
b) low
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Micro turbines are more efficient at low power levels when compared to reciprocating engines. As the size of micro gas turbines is less the total power produced is also less when compared to reciprocating engines.

8. Micro turbines use _______ bearings.
a) air & journal
b) journal
c) air
d) none of the mentioned

View Answer

Answer:c [Reason:] Micro turbines use air bearings. As journal bearings are huge in size when compared to air bearings and weight of air bearings is also less.

9. Micro turbines can also use magnetic bearings.
a) True
b) False

View Answer

Answer: a [Reason:] High temperatures and high speed of micro turbines make usage of ball bearings impractical and so micro turbines can be used with air bearings or magnetic bearings.

10. Throttling of the fuel in gas turbines is impractical.
a) True
b) False

View Answer

Answer: a [Reason:] Battery is used as a buffer in micro turbines for storing electricity and hence throttling is not required in micro turbines.

Set 3

1. _______ can be used as fuels in gas turbines.
a) Natural gases
b) petroleum
c) Diesel
d) All of the mentioned

View Answer

Answer: d [Reason:] Natural gases,petrol,diesel etc can be used as fuels in gas turbines. Gas turbines requires liquids with high specific heat as fuels.

2. Vanadium content in the fuels used for gas turbines should be ________
a) high
b) low
c) zero
d) none of the mentioned

View Answer

Answer: b [Reason:] Vanadium content must be low in the fuels used for gas turbines. Excessive vanadium content in the fuel leads to decrease in the specific heat of the fuel.

3. Fuels used in gas turbines should have _____ ash content.
a) low
b) high
c) zero
d) none of the mentioned

View Answer

Answer: a [Reason:] Fuels used in gas turbines should have low ash content. When ash content is more calorific value of fuel gets decreased.

4. Gas turbine fuels congeal at ____ degrees are used in Locomotives.
a) -20
b) -10
c) -5
d) None of the mentioned

View Answer

Answer: c [Reason:] Gas turbine fuels congeal at -5 degrees are used in locomotives. Congealing temperature is the temperature at which the fuel freezes.

5. Fuels that congeal at ______ degrees are used in automobiles.
a) -12
b) -15
c) -20
d) None of the mentioned

View Answer

Answer: a [Reason:] Fuels that congeal at -12 degrees are used in automobiles. Fuels used in gas turbines in automobiles has a freezing point of -12 degrees.

6. ______ oil can also be used to operate gas turbine power plants.
a) Leaded
b) Non leaded
c) Crude fuel
d) None of the mentioned

View Answer

Answer:c [Reason:] Crude fuel oil can also be used to operate gas turbine power plants. Crude oil is the unrefined petroleum.

7. Water soluble salts are also removed from the fuels used in gas turbines.
a) True
b) False

View Answer

Answer: a [Reason:] Water soluble salts are also removed from the fuels used in gas turbines. If the salts are not removed there is a chance for surge formation.

8. lead content must be ______ in gas turbine fuels.
a) high
b) low
c) zero
d) none the mentioned

View Answer

Answer: b [Reason:] Lead content must be low in gas turbine fuels. If the lead content is increased it decreases the calorific value of the fuel.

9. Power loss will be _____ if impurities are present in gas turbine.
a) zero
b) less
c) high
d) none of the mentioned

View Answer

Answer: c [Reason:] If impurities are present in fuel it consumes much heat to start combustion and hence power loss takes place.

10. Inhibitors are added to attack the ash developed by combustion of vanadium in gas turbine fuels.
a) True
b) False

View Answer

Answer: a [Reason:] Inhibitors are added to attack the ash developed by combustion of vanadium in gas turbine fuels. Inhibitors reacts with vanadium and make them easy combustible during combustion.

Set 4

1. The reference material or time selected to use in making the calculation in a problem is called
a) Basis
b) Dimension
c) Unit
d) None of the mentioned

View Answer

Answer: [Reason:] The reference material or time selected to use in making the calculation in a problem is called basis.

2. What is the mass fraction of Na atom in NaOH molecule?
a) 0.33
b) 0.66
c) 0.575
d) 1.150

View Answer

Answer: a [Reason:] Take basis: 1 kg mole of NaOH.

3. What is the mole fraction of Na atom in NaOH molecule?
a) 0.33
b) 0.66
c) 0.575
d) 1.150

View Answer

Answer: c [Reason:] Take basis: 1 kg mole of NaOH.

4. A high energy producing gas contains the following mixtures of gases, 20% H2O, 40% CH4 and 40% CO2. The average molecular weight of the gas is?
a) 25.6
b) 26.6
c) 27.6
d) 28.6

View Answer

Answer: c [Reason:] Take a basis 100 kg mole and calculate the total weight of the gas for 100 kg mole. Next step, dividing it by 100 kg mole get the molecular weight of the gas.

5-6. Consider a gas contains N2(70%), O2(25%) and SO2(5%).
5. What is the composition of the gase N2 on an SO2-free basis?
a) 0.78
b) 0.22
c) 0.70
d) 0.25

View Answer

Answer: a [Reason:] First take a basis of 100 mole and then we get the moles of each gas. Next step is to eliminate 5 moles of SO2 and then calculate the composition of the gas.

6. What is the composition of the O2 gas on an SO2-free basis?
a) 0.78 and 0.22
b) 0.22 and 0.78
c) 0.70 and 0.25
d) 0.25 and 0.78

View Answer

Answer: a [Reason:] First take a basis of 100 mole and then we get the moles of each gas. Next step is to eliminate 5 moles of SO2 and then calculate the composition of the gas.

7. Two students are calculating the average weight of a gas, containing N2 and other gases. Student-1 takes the actual molecular weight of N2(28) and student-2 takes it wrong N2(14). The calculated molecular weights by both of them are 36.8 and 31.2 respectively.
What is the percentage of N2 in the mixture?
a) 5%
b) 10%
c) 15%
d) 20%

View Answer

Answer: b [Reason:] Take a basis of 1 mole of the gas and make two molecular weight equations, then calculate the percentage of N2.

8-10. NaOH is there in a test tube,
8. What is the mass fraction of Na in the sample?
a) 0.575
b) 0.85
c) 1.25
d) 2.28

View Answer

Answer: a [Reason:] Take basis as 1 Kg mole of Na, mass fraction = 23/40.

9. What is the mass fraction of O in the sample?
a) 0.2
b) 0.4
c) 0.6
d) 0.8

View Answer

Answer: b [Reason:] Take basis as 1 Kg mole of Na, mass fraction = 16/40.

10. What is the mole fraction of H in the sample?
a) 0.33
b) 0.66
c) 0.99
d) 2.00

View Answer

Answer: a [Reason:] Take basis as 1 Kg mole of Na, mole fraction = 1/3.

Set 5

1. Representation of the different phase of a compound on a two or three dimensional graph is
a) Block diagram
b) Equilibrium diagram
c) Phase diagram
d) None of the mentioned

View Answer

Answer: c [Reason:] Representation of the different phase of a compound on a two or three dimensional graph is called Phase diagram.

2. A non-condensable gas is found
a) Above the critical point
b) Below the critical point
c) On the critical point
d) None of the mentioned

View Answer

Answer: a [Reason:] A non-condensable gas is found above the critical point.

3. Incorrect statement about a phase diagram is
a) Phase diagram are based on equilibrium conditions
b) For phase equilibrium, it is assumed that the phase doesn`t remain invariant
c) Phase diagrams enable to view the properties of two or more phases as a function of temperature, pressure and other variable
d) None of the mentioned

View Answer

Answer: b [Reason:] For phase equilibrium, it is assumed that the phase remains invariant.

4. The one P-T-V combination at which solid, liquid and vapour are in equilibrium, is called
a) Critical point
b) Triple point
c) Saturation point
d) None of the mentioned

View Answer

Answer: b [Reason:] The one P-T-V combination at which solid, liquid and vapour are in equilibrium, is called Triple point.

5. If the vapour and liquid of a pure component are in equilibrium, the equilibrium pressure is called
a) Partial pressure
b) Vapour pressure
c) Liquid pressure
d) None of the mentioned

View Answer

Answer: b [Reason:] If the vapour and liquid of a pure component are in equilibrium, the equilibrium pressure is called Vapour pressure.

6. At a given temperature there is only ________ pressure at which the vapour and liquid phases of a pure substances may exist in equilibrium.
a) Three
b) Two
c) One
d) None of the mentioned

View Answer

Answer: c [Reason:] At a given temperature there is only one pressure at which the vapour and liquid phases of a pure substances may exist in equilibrium.

7. The change of phase from liquid to vapour is called
a) Boiling
b) Melting
c) Condensation
d) None of the mentioned

View Answer

Answer: a [Reason:] The change of phase from liquid to vapour is called Boiling.

8. __________ is the temperature at which a liquid just start to vaporize.
a) Critical point
b) Bubble point
c) Triple point
d) Saturation point

View Answer

Answer: b [Reason:] Bubble point is the temperature at which a liquid just start to vaporize.

9. Find the incorrect statement for condensation
a) The change of phase from vapour to liquid
b) Occurs at constant temperature and pressure
c) The process appears as a point in in a P-T diagram
d) All of the mentioned

View Answer

Answer: d [Reason:] All a, b & c are correct for condensation.

10.______ is the temperature at which the vapour just begins to condense at a specified pressure, that is the value temperature along the vapour pressure curve.
a) Dew point
b) Bubble point
c) Triple point
d) Critical point

View Answer

Answer: a [Reason:] Dew point is the temperature at which the vapour just begins to condense at a specified pressure, that is the value temperature along the vapour pressure curve.