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Multiple choice question for engineering

Set 1

1. Which of the following is not a type of steam turbine?
a) Impulse turbine
b) Reaction turbine
c) Pelton wheel turbine
d) Axial flow type turbine

View Answer

Answer: c [Reason:] Pelton wheel turbine is a water turbine. Impulse and reaction turbines are the steam turbines characterized by the action of steam on moving blades. Axial and radial flow turbine and steam turbines are characterized by type of flow of steam over blades.

2. Which statement about impulse turbine is true?
a) Steam expands over blades
b) Steam expends completely in stationary nozzels
c) Steam expends partially over nozzle and turbine blades
d) Steam expends over blades incompletely

View Answer

Answer: b [Reason:] In an impulse turbine the steam expands completely in the stationary nozzles. No pressure drop occurs over the moving Blade Runner. During expansion steam attains a high velocity and impinges against the blades fixed on the rotor Periphery resulting in the impulsive force on the moving blades which sets the rotor rotating.

3. Which statement about reaction turbine is false?
a) Steam does not expand in nozzle
b) Blades acts like nozzles
c) Steam expands as flows over the rotor blades
d) Steam continuously losses its heat as flows over the rotor blades

View Answer

Answer: d [Reason:] The expansion of steam in reaction turbine totally occurs when it flows over the turbine blades. The expansion of steam as it flows over the blades is adiabatic any friction losses between the steam and the blades are converted into heat which in turn will reheat the steam.

4. Reaction turbines are characterized by ___________
a) relatively low RPM and steam expension over nozzle
b) relatively high RPM and steam expension over nozzle
c) relatively low RPM and steam expension over rotor blades
d) relatively high RPM and steam expansion over rotor blades

View Answer

Answer: c [Reason:] In reaction turbine steam does not expand in nozzle but expands as flows over the rotor blades. Reaction turbines are characterized by relatively low RPM. As steam expands over the turbine blades, causes the reaction force over the turbine which rotates the turbine.

5. In condensing turbine what is the back pressure of the turbine?
a) Very high
b) Above atmospheric pressure
c) Equal to atmospheric pressure
d) Below atmospheric pressure

View Answer

Answer: d [Reason:] According to the back pressure steam turbines are classified into condensing and non condensing turbines. Where there is no use of exhaust steam, turbine is built as a pure condensing type turbine. In condensing turbine steam is reduced in pressure down to a vacuum pressure which is in accordance with the cooling water temperature.

6. The turbine in which steam enters the blade tip nearest the axis of the wheel and flows towards the circumference is called _____________
a) axial flow turbine
b) radial flow turbine
c) impulse turbine
d) non-condensing turbine

View Answer

Answer: b [Reason:] According to type of flow of steam the steam turbines used are of two types namely axial flow turbine and radial flow turbine. In axial flow turbine steam flows over the blades in a direction parallel to the axis of wheel. In radial flow turbine steam enters from blade tip near the axis of wheel and flows towards the circumference.

7. Majority of the turbines are axial flow type.
a) True
b) False

View Answer

Answer: a [Reason:] In axial flow type turbines the steam flows over the blades in a direction parallel to the axis of the wheel. In radial flow turbines the blades are arranged radially so that the steam enters at the blade tip nearest the axis of the wheel and flows towards the circumference.

8. Which turbines are employed for driving alternator at synchronous speed?
a) Central Station turbine
b) Reheating turbine
c) Extraction turbine
d) Extraction induction turbine

View Answer

Answer: a [Reason:] Central turbines are for driving the alternator at synchronous speed. In Reheating turbine steam is returned back to the boiler after partial expansion for superheating and then allowed to expand to back pressure. In extraction turbines steam leaves the turbine casing before the exhaust, for feed water heating.

9. Read the statements below.
I. The built up rotor is cheaper and easier to manufacture.
II. The high pressure and intermediate pressure rotors are always of integral type.
a) Only statement I is correct
b) Only statement II is correct
c) I and II are correct
d) I and II are wrong

View Answer

Answer: c [Reason:] A built-up rotor consists of a forged steel shaft on which separate forged steel discs are shrunk and keyed. In an integral rotor the wheels and shaft are formed from the solid forging. The built-up rotor is cheaper and easier to manufacture.

10. In velocity compounding the steam is expanded from the boiler pressure to condenser pressure in one set of stationary blades on nozzle.
a) True
b) False

View Answer

Answer: a [Reason:] In compounding a number of rotors in series, keyed on the same shaft, are employed and the steam pressure or the jet velocity is absorbed in steps as it was over the moving blades. Compounding is necessary for obtaining reasonable blade tip speed in turbines.

Set 2

1. Kaplan turbine is _____________
a) axial flow turbine
b) inward flow turbine
c) tangential flow turbine
d) mixed flow turbine

View Answer

Answer: a [Reason:] In Kaplan turbine water strikes the turbine blades axially. That’s why Kaplan turbine is an axial flow turbine. Kaplan turbines are special type of turbines for low head applications.

2. Pelton turbines are used for __________________
a) medium head applications
b) low head applications
c) in steam power plants
d) for high head applications

View Answer

Answer: d [Reason:] Pelton turbines are impulse turbines and are suitable for high head low flow plants. Pelton turbines consist of elliptical shaped buckets along its Periphery. Water is released from nozzle to the buckets of turbine.

3. Francis turbines are the type of _____________
a) reaction turbines
b) radial flow turbine
c) impulse turbine
d) axial flow turbine

View Answer

Answer: a [Reason:] Francis turbines are inward mixed flow type reaction turbines. Such turbines develop power partly due to velocity of water and partly due to difference in pressure acting on the front and back of the runner blades.

4. Operating head of Francis turbine is __________
a) less than 30
b) less than 70 m
c) 30 to 200 m
d) more than 200 m

View Answer

Answer: c [Reason:] Francis turbines are medium head(30 to 200 m) and medium flow turbines. Using it for low or high head will cause inefficient operation. Their life is about decades so maintenance cost is low.

5. Which of the following is not a reaction turbine?
a) Francis turbine
b) Kaplan turbine
c) Pelton wheel turbine
d) Propeller turbine

View Answer

Answer: c [Reason:] When the entire pressure of water is converted into kinetic energy in a nozzle and the jet thus formed drives the wheel then the turbine is called impulse turbine. Pelton turbine works in similar way, so it is an impulse turbine. Francis, Kaplan and propeller turbines are reaction turbines.

6. Inside pressure of which of the following turbine is equal to atmospheric pressure?
a) Fixed vane propeller turbine
b) Movable vane propeller turbine
c) Francis turbine
d) Pelton wheel turbine

View Answer

Answer: d [Reason:] Francis and propeller turbines are totally submerged in water, the turbine casing is full of water. As the water flows through the turbine blades, its pressure changes. Also the discharging water creates negative pressure below the turbine blades. Pelton turbines are fitted in open air and water Jet is forced into its blades by nozzel so it’s inside pressure is equal to atmospheric pressure.

7. Francis turbine is suitable for medium head hydroelectric power plant.
a) True
b) False

View Answer

Answer: a [Reason:] Francis turbines are medium head and medium flow turbines. Kaplan turbines are low head high flow turbines. Pelton turbines are high head and low flow turbines.

8. Which turbine has highest speed?
a) Pelton wheel turbine
b) Francis turbine
c) Impulse turbine
d) Kaplan turbine

View Answer

Answer: d [Reason:] Francis turbine has a specific speed of 60 to 300 rpm. Specific speed of Pelton turbine is lowest. Speed of Kaplan turbine is 2 to 3 times more than that of Francis turbine.

9. Governing mechanism used in case of Pelton wheel turbine is ________
a) guide vane
b) nozzle needle
c) control valve
d) dam gates

View Answer

Answer:b [Reason:] During load variation it is necessary to maintain the speed of the alternator constant. This is achieved by controlling the flow of water entering the turbine by the help of automatic adjustment of guide vanes for reaction turbine and the nozzle needle is in case of impulse turbine. Such an operation of speed regulation called governing and the system used to do this is called governor.

10. Guide vanes are used as governor in Kaplan turbine.
a) True
b) False

View Answer

Answer: a [Reason:] Guide vanes are used as governor in Francis and Kaplan turbines. These guide vanes controls the flow of water to the turbine and hence governs the speed of rotation of turbine. Under different loading conditions the speed of rotation of turbine is needed to be controlled for constant frequency output.

Set 3

1. How many layers are present in the OO design pyramid?
a) three
b) four
c) five
d) one

View Answer

Answer: b [Reason:] The four layers are: Subsystem layer, class and object layer, message layer and responsibilities layer

2. Which of the following early OOD methods incorporates both a “micro development process” and a “macro development process.” ?
a) Booch method
b) Rumbaugh method
c) Wirfs-Brock method
d) Coad and Yourdon method

View Answer

Answer: a [Reason:] The macro development process includes the architectural planning and micro developments process defines rules that govern the use of operations and attributes and the domain-specific policies for memory management, error handling, and other infrastructure functions.

3. Grady Booch, James Rumbaugh, and Ivar Jacobson combined the best features of their individual object-oriented analysis into a new method for object oriented design known as
a) HTML
b) XML
c) UML
d) SGML

View Answer

Answer: c [Reason:] The Unified Modeling Language (UML) has become widely used throughout the industry as the standard approach to OOD.

4. A design description of an object is known as a class
a) instance
b) object
c) case
d) both instance and object

View Answer

Answer: d

5. Which of the following is conceptually similar to objects?
a) PACKAGE
b) PROC
c) PRIVATE
d) None of the mentioned

View Answer

Answer: a [Reason:] A package is a namespace that organizes a set of related classes and interfaces.

6. A design description in OOD includes
a) Protocol Description
b) Implementation Description
c) Type Description
d) both Protocol and Implementation Description

View Answer

Answer: d

7. Which of the following is not an operation as per OOD algorithms and data structures?
a) operations that manipulate data in some way
b) operations that perform a computation
c) operations that check for syntax errors
d) operations that monitor an object for the occurrence of a controlling event

View Answer

Answer: c [Reason:] Operations that check for syntax errors is concerned with the programming language used, so it will be handled by the compiler.

8. Throughout the OOD process, a software engineer should look for every opportunity for creating new design process.
a) True
b) False

View Answer

Answer: b [Reason:] A software engineer should look for every opportunity to reuse existing design patterns whenever they meet the needs of the design rather than creating new ones.

Set 4

Here is a listing of advanced C interview questions on “Formatted Output” along with answers, explanations and/or solutions::”

1. What is the output of this C code?

  1.     #include <stdio.h>
  2.     int main()
  3.     {
  4.         int i = 10, j = 2;
  5.         printf("%dn", printf("%d %d ", i, j));
  6.     }

a) Compile time error
b) 10 2 4
c) 10 2 2
d) 10 2 5

View Answer

Answer: d

2. What is the output of this C code?

  1.     #include <stdio.h>
  2.     int main()
  3.     {
  4.         int i = 10, j = 3;
  5.         printf("%d %d %d", i, j);
  6.     }

a) Compile time error
b) 10 3
c) 10 3 some garbage value
d) Undefined behaviour

View Answer

Answer: c

3. What is the output of this C code?

  1.     #include <stdio.h>
  2.     int main()
  3.     {
  4.         int i = 10, j = 3, k = 3;
  5.         printf("%d %d ", i, j, k);
  6.     }

a) Compile time error
b) 10 3 3
c) 10 3
d) 10 3 somegarbage value

View Answer

Answer: c

4. What is the output of this C code?

  1.     #include <stdio.h>
  2.     int main()
  3.     {
  4.         char *s = "myworld";
  5.         int i = 9;
  6.         printf("%*s", i, s);
  7.     }

a) myworld
b) myworld(note: spaces to the left of myworld)
c) myworld (note:followed by two spaces after myworld)
d) Undefined

View Answer

Answer: b

5. What is the output of this C code?

  1.     #include <stdio.h>
  2.     int main(int argc, char** argv)
  3.     {
  4.         char *s = "myworld";
  5.         int i = 3;
  6.         printf("%10.*s", i, s);
  7.     }

a) myw
b) myworld(note:2 spaces before myworld)
c) myworld (note:2 spaces after myworld)
d) myw(note:6 spaces after myworld)

View Answer

Answer: d

6. What is the difference between %e and %g?
a) %e output formatting depends on the argument and %g always formats in the format [-]m.dddddd or [-]m.dddddE[+|-]xx where no.of ds are optional.
b) %e always formats in the format [-]m.dddddd or [-]m.dddddE[+|-]xx where no.of ds are optional and output formatting depends on the argument.
c) No differences
d) Depends on the standard

View Answer

Answer: b

7. Escape sequences are prefixed with.
a) %
b) /
c) ”
d) None of the mentioned

View Answer

Answer: d

8. What is the purpose of sprintf?
a) It prints the data into stdout
b) It writes the formatted data into a string
c) It writes the formatted data into a file
d) None of the mentioned

View Answer

Answer: b

9. The syntax to print a % using printf statement can be done by.
a) %
b) %
c) ‘%’
d) %%

View Answer

Answer: d

Set 5

1. Which of the following does not apply to cyaniding?
a) Requires less time
b) Operated at lower temperatures
c) Low corrosion resistance
d) Costly process

View Answer

Answer: c [Reason:] The cyaniding process is an expensive process of surface hardening of steels which is applied to produce automobile parts. It requires lesser time and lower temperatures than carburizing. It also lowers warping and distortion while increasing the corrosion and wear resistance.

2. Gas cyaniding is otherwise known as __________
a) Nitriding
b) Carbonitriding
c) Induction Hardening
d) Flame Hardening

View Answer

Answer: b [Reason:] Carbonitriding is a surface hardening process that involves the diffusion of nitrogen and carbon into the steel. Carbonitriding may also be called as gas-cyaniding or dry-cyaniding.

3. How long is the heating process for carbonitriding done for?
a) 1-2 hours
b) 2-10 hours
c) 12-20 hours
d) 24-30 hours

View Answer

Answer: b [Reason:] The carbonitriding process is carried out in a gas atmosphere furnace using a carburizing gas such as propane or methane mixed with ammonia. The workpiece is heated to 850oC in the mixture of gases for 2-10 hours followed by quenching and tempering.

4. At what temperature is the workpiece tempered in carbonitriding process?
a) 180oC
b) 360oC
c) 540oC
d) 720oC

View Answer

Answer: a [Reason:] The carbonitriding process is carried out in a gas atmosphere furnace using a carburizing gas.The workpiece is heated to 850oC in the mixture of gases for 2-10 hours. This is followed by quenching to increase hardness, then by tempering at 180oC for reducing the brittleness.

5. What is the case depth obtained in the cyaniding process?
a) 0.38 mm
b) 0.25 mm
c) 0.5 mm
d) 1.25 mm

View Answer

Answer: b [Reason:] Of all the diffusion surface hardening methods, carburizing provides the highest cast depth of 1.38 mm. This is followed by carbonitriding, nitriding, and cyaniding at 0.5 mm, 0.38 mm, and 0.25 mm correspondingly.

6. What is the hardness achieved in carbonitriding process?
a) HRC 35
b) HRC 65
c) HRC 105
d) HRC 140

View Answer

Answer: b [Reason:] Carbonitriding process of surface hardening results in a case depth of 0.5 mm and a hardness after heat treatment of HRC 65. Interestingly, carburizing and cyaniding also result in equal hardness after heat treatment.

7. What are the applications of nitriding?
a) Gears, camshafts
b) Valve guides and seatings
c) Chain links, nuts, bolts, and screws
d) Gears, nuts, bolts

View Answer

Answer: b [Reason:] Nitriding process provides an extreme hardness of the surface and a case depth of 0.38 mm. It is typically used for valve guides and seatings, and for gears.

8. Nitriding steels are tempered at about ________
a) 100-200oC
b) 300-450oC
c) 600-700oC
d) 800-950oC

View Answer

Answer: c [Reason:] Nitralloy steels are commonly used in nitriding process. These steels are hardened by oil quenching from 900oC and tempered at 600-700oCbefore nitriding.