Infosys Technical Interview Questions 2018

On this dashboard you will find Technical questions asked by Infosys in first round of interview.

We have collected Student Interview Experience form over 200 students and made list of most asked questions in the infosys interview and facts and pattern of interview.

We have also done time-analysis by asking a lot of HR’s about guidelines that they give to the interviewers

For CS/IT branches 

  1. Approx 40% time for C/OOPS/ C++ or Java
  2. 30% time for Coding questions(Find Coding Dashboard below)
  3. 20% time Core CS subjects like CN/DBMS/Software Engineering
  4. 10% time for final year Project based questiosn

For non-CS-IT Branches

  1. 50% time for C/OOPS/C++ or Java
  2. 30% time for Coding Questions(Find Coding Dashboard below)
  3. 10% time on Project Diagrams, theory, definitions
  4. 20% time for theory related to subject of your final year project

Mostly, for non-CS/IT people, the interviewer may not be from your branch he will google questions from the subject your project is related to. So, make sure that you visit first few pages of related subject to your project.

Infosys Technical Interview Questions for Freshers 2018

Below you will find the most asked Infosys Technical Interview Round Questions –

We did analysis of 300 and more interview experiences submitted by students for infosys on prepinsta and deduced some cool facts about Inofsys technical interview questions pattern –

Infosys Freshers Questions in Technical Interview Facts

Technical Interview Questions asked in InfosysPercentage Amount Duration Spent for section (CS/IT)Percentage Amount Duration Spent for section (Others)Difficulty Level Most asked Question
C1020MediumWhat is pre-processor in C
OOPS (C++/Java)3010HardDifference between Procedural and OOPS Language
Coding3030MediumFactorial of number by Recursion
Core Branch Specific Subjects2020MediumDepends on Branch to branch
Projects1010EasyDraw Circuit Diagram of project and explain each unit in detail

Infosys Vs other Mass hiring Companies Interview Process Comparison

  1. Technical
    1. Infosys like TCS, likes to go in Technical details of your Branch Projects, definitions, diagrams, code etc
    2. Other companies like Cognizant and Accenture specifically like to keep it non technical and focus more on English.
  2. Duration of Interview
    1. While in Accenture and CTS the duration of Interview is around 15 mins
    2. For Infosys it ranges anywhere between 25 mins to 40 mins
  3. Coding Questions
    1. Companies like Accenture and Deloitte don’t ask coding questions at all
    2. But, Infosys, Wipro will ask you basic coding questions like Palindrome, pattern printing etc even if you’re from Non CS IT round. You will find Coding Questions asked in Infosys on our Infosys Coding Interview Dashboard here.
  4. C / OOPS Questions
    1. Infosys just like TCS, does ask C / OOPS concept to all Branches. Well, you’re applying to an IT company they expect you to know a little about C / OOPS theory.
    2. Companies like Accenture, Deloitte don’t ask C / OOPS concept. But, their training is very difficult, so even if you get selected. You need to learn all about coding and technical aspects
  5. Freedom of Topic Selection
    1. All bulk companies give freedom of topic selection to you, generally the interviewer will ask you the favourite subject and will ask questions from that, or will ask you the questions from topics, chapters and projects mentioned in your Resume.

While you’re giving your interview, the interviewer side by side is filling your Grades based on your answers. The following is the grade sheet used by Infosys –

  1. OutStanding – A
  2. Good – B
  3. Average – C
  4. Below Average – D

As you can see above there is no Grade E and F. For Infosys. We have seen that only people who get hired are, who score all A’s and B’s.

The interviewer will scale you on the following points-


  • English Speaking
  • Coding Skills
  • Technical Skills
  • Overall


  • English Speaking
  • Team work capabilities
  • Cultural Fit
  • Flexibility
  • Infosys’s Interview is very uncomforting for the interviewee.
  • They just like to get the job done and go straight ahead with the questions.
  • We don’t see any water being offered to students, like in other bulk companies.
  • No Chocolates being offered like in Accenture and Cognizant.
  • They don’t also ask questions like – how long have you been waiting etc to make student comfortable and they don’t care about your time.
  • What is the most difficult subject you have studied in college?
    Suppose you know only java and they can ask questions like ‘Within the next one year artificial intelligence is only going to rule the world but you are saying that you only know Java’.
  • What is the latest technology you know?
  • Tell me about the subjects what you learnt in college these four years?

First Question Always in Infosys Interview is – 

What are your strong or most comfortable programming language and rate yourself out of 10?

This is the question asked by most of the interviewers. This question decides the direction of the interview. You have to answer the programming language which you know and prepared for the interview like C, C++, JAVA and so on. For the rate yourself part, always be confident and rate yourself high but at the same time be honest as this shows your level of confidence and honesty. Only based on this question, you will be questioned from your preferred language.

  • Why is C called procedural language?
    • Because C programs follow a procedure of steps written in it, called functions. It follows a top-down approach i.e. much importance is given to flow of program rather than on data on which functions operate. On the other hand, Java/C++ are object oriented languages. They have a bottom up approach.
  • What is the difference between procedural and object oriented programming?
    • Procedural – follows a step-by-step approach to break down a task into a collection of variables and routines (or subroutines) through a sequence of instructions. Each step is carried out in order in a systematic manner so that a computer can understand what to do. The program is divided into small parts called functions and then it follows a series of computational steps to be carried out in order. It follows a top-down approach to actually solve a problem, hence the name. Procedures correspond to functions and each function has its own purpose. Dividing the program into functions is the key to procedural programming. So a number of different functions are written in order to accomplish the tasks.
    • Object Oriented – OOP is a high-level programming language where a program is divided into small chunks called objects using the object-oriented model, hence the name. This paradigm is based on objects and classes.

      Object – An object is basically a self-contained entity that accumulates both data and procedures to manipulate the data. Objects are merely instances of classes.
      Class – A class, in simple terms, is a blueprint of an object which defines all the common properties of one or more objects that are associated with it. A class can be used to define multiple objects within a program.
      The OOP paradigm mainly eyes on the data rather than the algorithm to create modules by dividing a program into data and functions that are bundled within the objects. The modules cannot be modified when a new object is added restricting any non-member function access to the data. Methods are the only way to assess the data.

  • Why do you use stdio.h before the program?
    • stdio stands for “standard input output”. So, #include is like including this standard input output library for your part of code. This way, you can use the IO functions available viz. printf and scanf. Since this is done before your code processing starts, it’s a pre-processor directive. 
  • What is the use of return 0?
    • In C and C++ programs, generally the main function is of type int and therefore it should return an integer value. The return value of the main function is considered the “Exit Status” of the application. So if we return 0 then the programs completes with integer return type.
  • What is the use of getch() function?
  • What is a do while loop?
  • What is a switch case?
  • Who created C language?
  • Why is the use of printf?
  • Difference between int and double?
  • What are the limits of int datatype?
  • What is the size of char data type?
  • What is a data type?
  • What is a pointer on pointer?
    • It’s a pointer variable which can hold the address of another pointer variable. It de-refers twice to point to the data held by the designated pointer variable. Eg: int x = 5, *p=&x, **q=&p; Therefore ‘x’ can be accessed by **q.
  • Can a program be compiled without main() function?
    • Yes, it can be but cannot be executed, as the execution requires main() function definition.
  • What is the difference between local variable and global variable in C?
    • Local variable: A variable which is declared inside function or block is known as local variable.
    • Global variable: A variable which is declared outside function or block is known as global variable.
  • What is recursion in C?
  • What are the usage of pointer in C?
    • Accessing array elements
    • Dynamic memory allocation
    • Call by Reference
    • Data Structures like tree, graph, linked list etc.
  • What is NULL pointer in C?
    • A pointer that doesn’t refer to any address of a value but NULL, is known as NULL pointer. For example: int *p=NULL;

First Question Always in Infosys Interview is – 

What are your strong or most comfortable programming language and rate yourself out of 10?

This is the question asked by most of the interviewers. This question decides the direction of the interview. You have to answer the programming language which you know and prepared for the interview like C, C++, JAVA and so on. For the rate yourself part, always be confident and rate yourself high but at the same time be honest as this shows your level of confidence and honesty. Only based on this question, you will be questioned from your preferred language.

  • What is the difference between C and Java?

    Java is the object-oriented programming language whereas C is the procedural language.
    Java supports method overloading whereas C does not support overloading at all.
    If an error occurs there is a concept called exception handling which is there in Javabut in C there is no concept like that.
    Java does not support preprocessors but C does.
    If the memory is allocated in C it has to be freed with the help of malloc() or free() library calls but Java uses the garbage collector to delete the objects that are no longer have any reference to them.

  • Explain the OOP concepts in C++.

    Object-oriented programming main concept is to implement real-world entities and binds data and functions which operate on them so that no other part of the code can access the data except that function. Also explain the objects, class, inheritance, polymorphism, encapsulation, and abstraction. Usually, everyone knows the basic definition but when it comes to giving real-world examples, they struggle. Hence, make sure that you can provide some real-world examples which you can relate to.

  • What is an Object in OOPS?

    Objects are runtime entity with some characteristics. For example, we can take fruits like banana, apple, oranges here. Each and every fruit has some characteristics like different shape, colour, odour. This is what we call as objects.

  • What is a Class in OOPS?

    Class is a user-defined data type and it is the blueprint of data and functions. We can take the same example fruits. Here, the fruit is the class and the different types of fruits which are available are the objects because within the class the objects are defined. So we can say that the instance of the class is an object.

  • Explain about Inheritance with an Example?

    Deriving the properties of the base class from the derived class is known as Inheritance. Here we can take an example of a parent and the child. All the properties of the father are inherited by son because of the gene factor which is present. There is a famous quote saying “Like Father Like Son”.

  • What is Polymorphism?

    The process of representing one form in many other forms is called Polymorphism. Take yourself as an example. You behave like son in the home. If you are going to a shopping mall then you behave like a customer. In school, you behave like a student. So this is what is known as polymorphism taking different forms.

  • What is Encapsulation?

    Encapsulation is the process of wrapping up of data and methods in a single unit. Here we can take an example as a capsule. In the capsule, the medicine is present only inside.

  • What is Abstraction?

    Abstraction is the process of hiding the internal details to protect from unauthorized access and only the external appearance is known. We can take mobile as an example. We only know how to operate the mobile but don’t know the internal workings of it.

    So these are the OOP concepts with real time examples. But try to know the details of how it is used in the program and also you can write a program as the example and show it to them. This concept is same in Java also and this is the most important question in interviews. So basically compare and study it will be very easy and you will not forget the concept.

  • What is Platform Independent?

    Platform independent means it can run on any OS without even changing the source code again and again. So once you write your code, you need not modify it according to the OS in platform independent languages. Java is platform independent, not C or C++.

  • What is Preprocessor in C/C++?

    Preprocessors are programs that process your code before the compilation. Preprocessor programs are available which provides preprocessor directives and tells the compiler to preprocess the code before compiling and it begins with the # symbol.

  • What do you mean by access specifiers ?
    • Access specifiers are used to define how the members (functions and variables) can be accessed outside the class. There are three access specifiers defined which are public, private, and protected
      • private: Members declared as private are accessible only with in the same class and they cannot be accessed outside the class they are declared.
      • public: Members declared as public are accessible from any where.
      • protected: Members declared as protected can not be accessed from outside the class except a child class. This access specifier has significance in the context of inheritance.
  • What do you mean by storage classes?
    • Storage class are used to specify the visibility/scope and life time of symbols(functions and variables). That means, storage classes specify where all a variable or function can be accessed and till what time those variables will be available during the execution of program.
  • How many ways are there to initialize an int with a constant?
    • Two. There are two formats for initializers in C++ as shown in the example that follows. The first format uses the traditional C notation. The second format uses constructor notation. int foo = 123; int bar (123);
  • What is a constructor?
    • Constructor is a special member function of a class, which is invoked automatically whenever an instance of the class is created. It has the same name as its class.
  • What is destructor?
    • Destructor is a special member function of a class, which is invoked automatically whenever an object goes out of the scope. It has the same name as its class with a tilde character prefixed.
  • What is an explicit constructor?
    • A conversion constructor declared with the explicit keyword. The compiler does not use an explicit constructor to implement an implied conversion of types. It’s purpose is reserved explicitly for construction. Read more: c++ interview questions and answers for freshers.
  • What is a friend function why do we use it?
  • What is data abstraction?
  • What is data encapsulation?
  • What is operating overloading?
  • What is data abstraction?
  • What advantage do C++ have over C?

For mechanical branch, first you will be asked questions on C/OOPS and then since your interviewer may or may not be from your branch.

He will ask your favourite subject and will ask questions from it.

Post which he will surely ask about your final year project and will ask you to make diagrams, definitions from it.

We analysed 200+ Interview Experiences submitted by students who gave interview for Infosys, these were the top questions asked by Interviewers to Mechanical Students –

Note – Interviewer may or may not be from Mech branch so he will most likely google questions to ask from you.

1. Why excess air is required to burn a fuel completely ?

Answer: Excess air is required to ensure adequate mixing of fuel and air, avoid smoke, minimize slagging in coal burning, and to ensure maximum steam output.

2. What is factor of evaporation ?

Answer: It is the ratio of heat change from feed water to steam and the heat of vaporization of steam at atmospheric pressure.

3. Materials which absorb neutrons and produce fissionable material are called ?

Answer: Fertile materials, such as U28 and Th22.

4. What is the process which produces fissionable material from a fertile material ?

Answer: Breeding.

5. What is burn up in connection with fissionable material ?

Answer: Burn up corresponds to destruction of fissionable material when it undergoes nuclear fission.

6. What kind of nuclear fuel is used in Narora, Kalapakkam and Rana Pratap Sagar nuclear plants ?

Answer: Natural uranium.

7. Which type of plant will you recommend for remote location if power is required in six to twelve months time ?

Answer: Diesel engine power plant.

8. Under what condition a nuclear reaction is said to be critical ?

Answer: For critical condition, the reaction should continue at a steady rate which is possible when rate of production of neutrons is same as the combined rate of absorption of neutrons and the rate of leakage of neutrons.

9. If a nuclear reactor generates more fuel that it consumes, it is called ______ ?

Answer: Fast breeder reactor.

10. Natural uranium contains only 0.7% U25 which is capable of switching chain nuclear reaction. How this percentage is increased ?

Answer: Percentage of U25 in natural uranium is increased by a process called uranium enrichment.

11. Why the vane passages are gradually increased in size in successive wheels in steam turbine ?

Answer: The velocity of steam decreases in successive stages and to accommodate same flow per unit time, the area of flow must increase.

12. At what pressure and temperature the density of water and steam is same ?

Answer: At 225 kg/cm2 and 74.6° C.

13. What is the latent heat of evaporation at critical point ?

Answer: Zero.

14. How much space steam will occupy at atmospheric pressure corresponding to 1 kg of water ?

Answer: 100 times the space occupied by 1 kg of water.

15. What is meant by quality of steam ?

Answer: It refers to amount of unevaporated moisture in steam. If steam is perfectly dry, it’s quality is 100%.

16. What is diagram efficiency in steam turbine ?

Answer: Diagram efficiency = Change in K.E./kg / Energy suppled/kg.

17. What do you understand by effectiveness of heat exchanger ?

Answer: Effectiveness of heat exchanger = actual heat transfer/maximum possible heat transfer.

18. If superheat and condenser temperatures are unchanged and if pressure of steam is increased, then what happens to dryness fraction of steam after isentropic expansion ?

Answer: It will decrease.

19. As pressure of steam is increased, why reheating is necessary?

Answer: As pressure is increased, the dryness fraction of steam lowers on isentropic expansion. Therefore, steam has to be reheated after partial expansion so that dryness fraction remains within limits after expansion.

20. What is boundary layer thickness in free convection case ?

Answer: Velocity of fluid flow at solid surface is zero and it increases rapidly as distance from solid surface becomes greater, reaches a maximum value and then decreases to that of undisturbed fluid. The distance between the solid surface and point where boundary layer velocity equals undisturbed flow (edge) is called boundary layer thickness.

21. What do you understand by forced convection ?

Answer: When convection heat transfer occurs between a solid body and a fluid and where circulation of fluid is caused and controlled by some mechanical.

22. In radiative heat transfer, a gray surface is one whose emissivity is _____ ?

Answer: Independent of wavelength.

23. What is the effect of water injection and steam injection in gas turbine of heat rate and power output ?

Answer: Water injection results in higher mass flow rate through turbine section and as rich electrical output is increased. However it increases gas turbine heat rate because of the additional heat consumption required to vaporise the water.

Steam injection increases power output and decreases heat rate because of its higher energy entering the combustion zone.

24. Water/steam injection in gas turbines increases power output. What is the limit and reasons for same ?

Answer: Water/steam injection is not allowed beyond 5% of compressor flow to avoid flame out in combustion and to minimise operating cost and impact on inspection intervals.

25. What are the advantages and drawbacks of centrifugal compressor and axial flow compressors in gas turbines?

Answer: Centrifugal compressors have following advantages :

—short length due to high pressure ratio attained in a single stage.

—simple in design, easy to manufacture, rugged in construction, less costly.

—more reliable in operation under all operating condition.

—less susceptible to the effects of deposits left on flow path.

—less sensitive to the fouling of the flow path.

—Good efficiency over a wide range of operation.

Drawback is larger cross-section area for same capacity and its unsuitability for high pressure ratios.

Axial flow compressor is more popular due to high delivery capacity, high compression ratio due to many stages, high efficiency (85-90%), low cross sectional area. Its drawback is sophisticated design and appreciable length due to large number of stages, narrow operating range for good efficiency, higher weight and cost, high starting power.

26. What is the difference between pinch point and approach point in connection with heat recovery steam generator (IIRSG) ? How they affect performance of IIRSG ?

Answer: Pinch point is the temperature difference between the gas turbine exhaust leaving the evaporator section and the saturation temperature of steam at corresponding pressure (drum operat¬ing pressure). Approach point is the temperature difference between the temperature of steam corre¬sponding to drum operating pressure and water temperature leaving the economiser. Both these vari¬ables affect the steam production and the cost and effectiveness of HRSG.

If pinch point is lower, total heat recovered in HRSG in higher and steam generation is also high. However lowering pinch point requires more heat exchange surface and increase in cost and draft side loss. Its optimum value is 8-10°C.

Lower is approach temperature, higher is steam production in economiser due to flashing which needs to be avoided for long life of tubes. Higher approach temperature increases the surface in evaporator section and assures higher stability.

27. How the efficiency of heat recovery in IIRSG increased ?

Answer: It can be increased by generating steam at more than one pressure.

Further improvement is possible by heating make up water/condensate in HRSG, generating low pressure saturated steam or dearation steam in HRSG using a low pressure evaporator, preheating the make up water in a heat exchanger before it enters deaerator, and circulate more water than necessary through the economiser and recirculate excess to the deaerator.

28. NO.,, reduction in gas turbines is challenge to meet environmental regulations. What measures are taken in this regard ?

Answer: NO* in gas turbines is controlled by (a) injecting water/steam into combustor, (6) using selective catalytic redaction (SCR) and non-catalytic reduction system (NRS), and (c) better combustor design.

29. What is the difference between fuel NOx and thermal NOx ?

Answer: Fuel NO* is formed by the gas phase oxidation of char nitrogen (CN~ compounds) in the fuel and thermal NO* is formed by high temperature reaction between the nitrogen and oxygen in the combustion air.

30. How steam/water injection in combustion zone lowers NOx formation.

Answer: It lowers the flame and gas temperatures.

31. What are disadvantages of injecting steam/water in combustion zone in gas tur¬bine ?

Answer: —Increased CO at lower loads

—Increased fuel consumption

—Loss of extensively treated water

—Increased complexity of engine control

—Short life of major turbine components.

32. What for water/steam is injected in combustion zones of a gas turbine ?

Answer: Water/steam is injected to limit the amount of NOx formed by lowering the flame and gas temperatures.

33. What are improved low NOx combustors ?

Answer: Dry low NOx combustors result in improved air/fuel mixing and reduced flame temperature. The main type are lean premixed combustors, rich/quench lean combustors and catalytic combustors. Variable guide vanes are used to control the fuel-air mixture. In one design combustion chamber is designed into a series of small, lean premixed chambers.

34. What is selective catalytic reduction (SCR) method for NO* control in gas turbines ?

Answer: SCR is a post combustion method in which a catalyst is installed in flue gas where temperature could be of the order of 15-400°C. It enables vaporised NH to react with NO* in exhaust gas to form N2 and H20. Vaporised NH is injected into exhaust gases before it passes through the catalyst bed. This process can achieve in excess of 90% NOx reduction.

35. What catalyst is used in SCR process for control of NOx in gas turbines ?

Answer: V2O5 supported by titanium or a mixture of titanium and silica is generally used as catalyst. Oxides of Ti and Mo are often incorporated as moderators.

36. Measure to minimise formation of NOx inhibit complete combustion and this results in formation of CO and voltatile organic compound (VOCs). How these are controlled ?

Answer: Catalytic oxidation, a post combustion treatment at 470°-600° temperature is used to reduce emission of CO and VOCs.

37. It is usual practice to report performance characteristics of gas turbine at ISO conditions. What are these ?

Answer: ISO conditions for GT performance are : Ambient dry bulb temperature : 15°C, Relative humidity – 60%. Ambient berometric pressure 1.0 kg/cm2.

38. Which parameters influence the heat rate of gas turbines and how ?

Answer: Various parameters affecting heat rate of GT are :

(i) Lower the gas turbine inlet temperature, lower the heat rate.

(ii) Higher the compression ratio, lower the heat rate.

(iii) Higher the turbine firing temperature, lower the heat rate.

(iv) Lower the exhaust temperature, lower the heat rate.

(v) Exhaust gas flow, inlet pressure loss, exhaust pressure loss also affect heat rate.

39. Which parameters influence the performance of gas turbines ?

Answer: Ambient conditions, inlet/exhaust pressure losses, fuels, and water/steam injection flow rates’influence the performance of gas turbines.

40. Why the efficiency of superheat Rankine cycle is higher than that of simple Rankine cycle ?

Answer: Because the mean temperature of heat addition is higher for superheat cycle.

41. A Carnot cycle is to be designed to attain efficiency of 0.75. If temperature of

high temperature reservoir is 727°C, then low temperature reservoir will have to be maintained at______°C ?

Answer: – 2°C.

42. A gas having a negative Joule-Thompson coefficient, when throttled, will become …. ?

Answer: hotter.

43. What is boundary layer thickness in turbulent boundary layer ?

Answer: In ease of turbulent boundary layer, boundary layer thickness is defined as the distance from solid surface at which the fluid velocity is 99% of the undisturbed free stream velocity. Near the surface of solid, there is laminar flow which changes to buffer zone and finally turbulent region.

44. Stirling cycle with regenerative arrangement and Carnot cycle operate within same temperature limits. What can be said about thermal efficiencies of these two ?

Answer: Thermal n of both will be same.

45. How does the stagnation temperature behave along a streamline in adiabatic flow with friction ?

Answer: It remains constant.

46. What is the frequency of secondary imbalance in four-stroke engine ?

Answer: Two times the engine speed.

47. What would be the order of boundary layer in pipe flow (i) laminar (ii) transition, and (iii) fully turbulent ?

Answer: In laminar flow, boundary layer extends right from surface upto centre. In fully turbulent it may extend 5-10% of radius only whereas in transition flow, boundary layer may be from 50-60% of radius of pipe.

48. In general how the boundary layer and local film coefficient of heat transfer are related ?

Answer: In general, the thinner the boundary layer, higher the value of local heat transfer film coefficient.

49. Out of constant volume and constant pressure line, which line on T-S diagram has higher slope ?

Answer: Constant volume.

50. A heat engine and a refrigeration cycle operate between two temperature limits T1 and T2(T1 > T2). The product of efficiency of heat engine and COP of refrigeration cycle will be ?

Answer: T2/TX.

51. A refrigerator and a heat pump are working on the reversed Carnot cycle between the same temperature limits. How COP of refrigerator and heat pump related ?

Answer: COP of refrigerator = COP of heat pump -1.

52. For a given set of operating pressure limits of a Rankine cycle, for which cycle the efficiency will be highest ?

Answer: For regenerative cycle which approaches Carnot cycle. 1

53. A steam pipe is to be insulated by two different insulating materials of same thickness. What arrangement is preferred ?

Answer: Material with lower thermal conductivity should be used for inner layer and material with higher thermal conductivity for the outer layer.

54. Why steam is in open space and water inside tube in condensers used in power plants ?

Answer: Overall heat transfer coefficient can be increased by increasing velocity of water in tube. Further steam needs more space due to higher specific volume.

55. A condenser of a refrigeration system rejects heat at a rate of 60 kW, while its compressor consumes a power of 15 kW. What will be the coefficient of performance of this system ?

Answer: .

56. Why a refrigeration compressor designed to operate with R22 refrigerant can’t be operated with R12 ?

Answer: Condensing pressure of R22 at any given temperature is higher than that of R12.

57. Leakage of Freon-12 refrigerant can not be easly detected, still it is preferred for air-conditioning. Why ?

Answer: Leakage of Freon-12 can’t attain total concentration but it has all desirable characteristics as good refrigerant.

58. In which season the process of humidification and in which season dehumidifi-cation is used in air-conditioning ?

Answer: Humidification in summer and dehumidification in winter.

59. What is the name given to combined process of cooling and humidifying ?

Answer: Evaporative Cooling.

60. Which refrigerant is used for ice plant and transport refrigeration ?

Answer: Ammonia and CO2 respectively.

61. Which cycle is used in vapour compression and gas cycle refrigerantion system ?

Answer: Brayton cycle, and Bell-Coleman cycle.

62. In what connection Wilson line and Willan’s line used ?

Answer: Wilson line represents saturation line on the Mollier diagram. Willan’s line is connected with determination of frictional power in IC engines.

63. How the characteristics of fuel like front end volatility, mid-range volatility and tail end volatility affect S.I. engines ?

Answer: These characteristics affect SI engines in cold starting, icing of carburettor and dilution in crankcase respectively.

64. What would be the approximate air fuel ratio at time of cold start, part load operation, full load, and idling ?

Answer: 10, 12.5 and 16 respectively.

65. Name pressure compounded and velocity compounded turbine.

Answer: Rateau and Curtis respectively.

66. What is the nature of curve in case of transfer of heat by conduction through a cylindrical wall and through a spherical wall ?

Answer: Logarithmic and hyperbolic.

67. What is radiosity ?

Answer: It is the rate at which radiation leaves a surface.

68. When the compressibility effects become significant in heat transfer problems in high speed flow ?

Answer: Compressibility effects usually become significant at gas flow velocities greater than 0.5 times the velocity of sound.

69. What is the name given to process of removing non condensables in steam and other vapour cycles ?

Answer: Deaeration process.

70. We often come across use of jet pumps in process industry ? What is the reason for this ?

Answer: Jet pumps are easy to maintain and can be used to transport gases, liquids and mixtures of both.

71. When it can be said that a fluid is Newtonian ?

Answer: When the shear stress is direcly proportional to velocity gradient.

72. Why alcohol can’t be used in diesel engine ?

Answer: Alcohol has low cetane number and thus its ignition is prevented by compression.

73. Out of 2 stroke SI engine, 4 stroke SI engine, and 4 stroke CI engine, how the brake thermal efficiency behaves if these are to be used for road vehicles ?

Answer: 4 stroke CI engine has highest brake thermal efficiency followed by 4 stroke SI engine and the 2 stroke SI has lowest brake thermal efficiency.

74. A jet engine is used to drive a vehicle. When its mechanical efficiency will be maximum ?

Answer: It will be maximum when vehicle speed approaches the relative velocity of gases at nozzle exit.

75. The knocking tendency in a S.I. engine can be reduced by increasing ?

Answer: Speed

76. How you define the emissivity of a body ?

Answer: Emissivity of a body is the ratio of the emitted radiant energy flux density to the emitted radiant energy flux density of a blackbody at the same temperature.

77. What is gray body ?

Answer: When the emissivity of material does not change with temperature, it is called gray body.

78. Define fin efficiency for extended heat transfer surfaces.

Answer: Fin efficiency is defined as the ratio of the mean temperature difference from surface to fluid divided by the temperature difference from fin to fluid at the base or root of the fin.

79. What are the harmful effects of sulphur in coal used for power generation ?

Answer: Sulphur in coal gives rise to number of ecological problems ranging from acid mine drainage to ash waste problems and air pollution due to SO2 emission. Emission of S02 is the cause of acid rain and is responsible for severe environmental damage.

80. What do you understand by microbial desulphurisation ?

Answer: Sulphur from coal can be removed by physical, chemical and microbial meAnswer: Microbial means has a number of advantages over other methods. Thiobalilius ferroxidans is the most widely used micro organism studied for coal desulphurisation. This bacteria can remove 90-98% of pyritic sulphur from coal. The reaction, of course, is slow and may take several days to several weeks to complete the reaction.

81. What causes rotation of steam turbine rotor ?

Answer: Rotation of turbine rotor is caused by centrifugal force created due to change of direction of fast flowing jet of steam.

82. What do you understand by the term coagulation ?

Answer: Impurities in water are usually in finely divided state which takes long time to settle and these usually pass through the filtering media. By adding certain chemicals (coagulants), gelatinous substances are formed which cause small particles to coalesce into groups large enough to be checked during filtering.

83. What is equivalent evaporation in a boiler plant ?

Answer: It is the amount of water that would be evaporated from water at 100°C to steam at 100°C by the same amount of heat which was actually absorbed by water and steam under operating conditions.

84. What is meant by balanced draft in boiler ?

Answer: Balanced draft refers to combination of forced and induced draft fans controlled to keep the furnace under slightly vacuum condition.

85. How is dryness fraction of steam measured ?

Answer: By using throttling calorimeter.

86. What is the difference between isentropic process and throttlinglprocess ?

Answer: In isentropic process, heat transfer takes place and in throttling process, enthalpy before and after the process is same.

87. What is the difference between pyrometer, pyranometer and pyrheliometer.

Answer: Pyrometer measures temperature by radiation principle. Pyranometer is used to measure total hemispherical solar radiation. Pyrheliometer is used to measure beam intensity by collimating the radiation.

88. What is the name given to useful part of available energy which is available for conversion to useful work ?

Answer: Exergy.

89. Does the area on PV diagram for a process represent work for both reversible and non-reversible process ?

Answer: No. Same is true for only reversible process.

90. Why work is considered as high grade of energy and heat as low grade energy ?

Answer: While work can be completely con¬verted to heat, heat can’t be converted fully to work.

91. When coluomb friction comes into existence between two surfaces ?

Answer: When there is relative motion between them.

92. Under what condition a number of forces acting at a point are in equilibrium ?

Answer: When sum of the resolved parts in any two perpendicular directions is zero.

93. What happens to two equal and opposite coplanar couples ?

Answer: They balance each other.

94. To slide a heavy block over a rough floor by a rope with minimum force by a man, at what angle the rope should be inclined with the level of floor ?

Answer: He should incline the rope with horizontal at angle of friction between floor and block.

95. A body is dropped from a certain height. If same body were to move down a smooth inclined plane from same height, which parameters will be same on reaching the ground ?

Answer: Velocity, kinetic energy and momentum.

96. A test specimen is stressed slightly beyond the yield point and then unloaded. What happens to its yield strength ?

Answer: It will increase.

97. Out of circular, square, channel, I sections, which is most economical for a component subjected to bending ?

Answer: I section.

98. What does the area under the stress-strain curve represent ?

Answer: Energy required to cause failure.

99. A tension member of certain diameter is to be replaced by a square bar of the same material. Side of square compared to diameter will be ?

Answer: Smaller.

100. A circular bar subjected to tension is designed for a particular safety factor. If both load and diameter are doubled, then factor of safety will be _____?

Answer: doubled.

Make sure that you know the following –

  1. Details of your final year project
  2. All circuit diagrams of your final year project
  3. Definitions on your final year project

Also, make sure that you 1 cover atleast 1 subject in details –

  • Interviewer will ask you your favourite subject and then ask you questions
  • The interviewer may or may not be from your branch so he will ask questions from Google if he is not.

Go to our Infosys ECE Interview Questions Dashboard here and study most asked ECE Questions for Infosys.

  • What is your area of interest?

This is also one of the questions asked in the Infosys Technical Interview. So depending on your area of interest, the questions may vary from person to person. You can say one or two areas of interest and make sure that whatever you have mentioned in the resume tell the same. Don’t say some random subjects. After this question, you will be questioned from your areas of interest. Answer them confidently. Suppose if you wrote DBMS as your area of interest then you should know all the concepts in DBMS. If you have given SQL then they may ask you to write SQL Queries or ask some theoretical questions like ” What is normalisation? Tell about the different normal forms present”.

So try to learn all the concepts of what you have mentioned in the resume and make sure that you understand it properly and prepare all the questions which is given above. Always remember that you are the one who is going to make the interview steer in the way which you want to be. So be confident and crack the interview.

Unlike other companies where they ask your feedback, where generally they will ask you about feedback and if you have any questions.

Infosys exit interview notations are not there, they will just ask you to send the next candidate.

  • Tell me the details of the project you have done?
  • Draw the circuit diagram of your project
  • Explain your final year project
  • What are the social benefits if any on your project

They generally ask like this – 

Explain your project.

This is the sure Infosys technical interview question asked to every candidate. So, be prepared to talk about the project you have done and try to explain them in a way that they can easily understand it. Even if they ask you to write the code of the project you should have the ability to at least explain the logic in detail.

Below are the Topics that will be only asked to CS/IT/MCA branches etc in Infosys –

  • He asked the sql query i.e to select top 3 rows from a student table arranged in descending order. he asked normalization question also. a table was given and I have to tell the table is in which nf. then the difference between 2nf and 3nf (Submitted by Student)
  • What is Normalisation?

    Normalisation is the process of organizing the data in the database basically to remove the redundant data i.e. Copy of the data and make sure that only related data got stored in the table. The types of Normalisation are as follows:

    First Normal Form (1NF): The 1NF rules for an organized database are as follows:
    Eliminate duplicative columns from the same table.
    Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).

    Second Normal Form (2NF): Once the database is organized according to the 1NF rules, 2NF rules further addresses the concept of removing duplicative data. These rules are as follows:
    Meet all the requirements of 1NF.
    Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
    Create relationships between these new tables and their predecessors through the use of foreign keys.
    Third Normal Form (3NF): The 3NF rules are as follows:
    Meet all the requirements of 2NF.
    Remove columns that are not dependent upon the primary key.

    Primary Key: During the design phase of the database, architects delineate entities and how these entities related to each other. Delineation provides the basis for all Relational Database Management Systems (RDBMS) design. Each entity should have its own unique identifier, which is known as the primary key. 
    Boyce-Codd Normal Form (BCNF or 3.5NF):: It also referred to as the “third and half (3.5) normal form” as adds one more requirement to the 3NF rule. The 3.5NF rules are as follows:
    Meet all the requirements of the third normal form.
    Every determinant must be a candidate key.
    Fourth Normal Form (4NF): The rules for the 4NF are as follows:
    Meet all the requirements of the third normal form.
    A relation is in 4NF if it has no multi-valued dependencies.

    In a DBMS, a trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE) occurs. Since triggers are event-driven specialized procedures, they are stored in and managed by the DBMS. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion.

  • He asked me software development life cycle
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