BARC Interview Experience

Before sharing my interview experience at Bhabha Atomic Research Centre (BARC) for the post of Scientific Officer (Computer Science), I must tell you that BARC shortlists candidates for interviews based on 2 mode – either through gate score or through written exam. I was shortlisted through written exam. I will give some brief description about the written exam and document verification which happens before the actual interview.

Written Exam :

The exam comprises of 100 questions of MCQ type having +3 for a correct answer and -1 for a wrong answer. So the total marks of the exam is 300. I don’t think you need special preparation for this exam if you are already preparing for GATE. You can just go through some basics of Software Engineering apart from studying GATE Syllabus. The important point to note for this exam (and for exams like ISRO) is the accuracy and not the number of questions attempted. Although the cutoff varies every year (139/300 in 2018, 183/300 in 2020) depending on the difficulty level of the exam, I guess anything between 65-70 questions with high accuracy is a good attempt.

Document Verification :

BARC sends you an email in which all the documents required on the date of interview is listed. Please read the e-mail very carefully and prepare all your documents as it can waste a lot of time there at the venue because firstly the network connectivity is very poor there and secondly to reach photocopy shop from the venue takes quite some time. I am going to list the documents required for verification-

  • All marksheets and certificates from 10th class onwards (original and 1 self-attested copy of each document)
  • Id proof (original and 1 self-attested copy)
  • CGPA/CPI to Percentage Conversion Document (if your college/university follows CGPA/CPI marking scheme)
  • GATE Scorecard (if you are shortlisted through gate cutoff)
  • To get reimbursement for your travel, you need Bus/Train/Flight Ticket on which the total price of the ticket should be mentioned, Blank cancelled cheque copy (Boarding pass is also required if you are travelling by plane).


We were told to report at 8 am in the morning. It was a big hall and students from different branches were gathered there. After all the document verification I went to the waiting room. After some time my name was called and I went inside the interview room. So, there were two panels of Computer Science. Mine was panel number 2. My interview started at around 12:50 pm in the afternoon. 6 senior scientists were sitting in a round table, the Chairperson mam sitting in the middle. She had the Q-form which we filled in the hall during document verification.

Chairperson: So Badal from where did u do your M.Tech?
Me: Told
Chairperson: What all subjects have you studied in your Masters?
Me: Told her a few subjects
Chairperson: We are going to ask you from your BTech subjects. Are you in touch with them?
Me: Yes Mam
Chairperson: Can you write your 5 favorite subjects on the board? 
Me: C, DS, SE, OS, DBMS (in the same order)
Chairperson mam moving her head to the person sitting on left

P1: So we will start with Data Structures first
Me: Ok Sir
P1: Can you tell any complex data structure you have studied?
Me: Sir, Graph
P1: And why according to you it is complex?
Me: In representation and implementation point of view
P1: But we can represent them using arrays then why complex?
Me: Told him about the time and space complexity issues  
P1: Okay, Can you tell what are the ways in which we can represent a graph?
Me: Sir, Adjacency Matrix and Adjacency List
P1: Draw a graph with some nodes, make an adjacency list and write C/C++ code for that?
Me: Drawn a graph with numbers as node.
P1: What will u store in these numbers?
Me: Sir vertices
P1: Give some applications of graph from real life and then tell what will you store in these nodes.
Me: Told him about Traveling Salesman Problem and explained the basic idea 
P1: Okay,  Write the code for adjacency list?
Me: Declared a structure for the list but got stuck at the nodes. He started giving me hints for representing node. I explained the idea again.
P1: Okay, Can you write the condition for Binary Search Tree?
Me: Answered
P1: Gave me a tree with some nodes and asked do you think this tree is a BST using your conditions only?
Me: No Sir, this condition is incomplete. We have to write some more checks.
Meanwhile, Chairperson mam pointing to P2 to move to other subject 
I tried explaining him some more checks, He said its okay I know you will write it if given some more time.

P2: Okay We will start with Operating System. What are the topics you have studied in OS?
Me: Answered (in the sequence starting from Process Management and ending with Disk Management and Protection)
P2: When you say management, what role does an OS do in management and what are all the things it manages?
Me: Answered
P2: What are all the algorithms you have studied in every part of OS?
Me: Starting From FCFS, SJF, SRTF, Round Robin (in CPU Scheduling), First Fit, Best Fit Worst Fit (in Memory Allocation), FIFO, Optimal,LRU (in Page Replacement), SSTF, LOOK, SCAN(in Disk Scheduling) 
P2: Why do we study a lot of algorithms, why not just stick with one?
Me: Told him that there are lot of pros and cons of every algorithm (with respect to CPU Scheduling)
P2: Which CPU Scheduling algorithm is better?
Me: Sir there are 2 things for selecting an algorithm (with respect to CPU Scheduling)- criteria and the mode(preemptive/non-preemptive) and with respect to that SJF and Round Robin is better but they have their pros and cons.
P2: Okay but how do we decide that this algorithm is better than the other? Are there any parameters?
Me: Told him about Average Turnaround Time, Waiting Time.
P2: What exactly is waiting time - the time from arrival till it got the CPU for the first time or the total time it waited for the CPU?
Me(After thinking for a while): Sir total time
P2: How do we compute it?
Me: Explained about Gantt Chart, Burst time, Completion time and formula to compute TAT and WT
P2: What is the difference between program size and process size? Are they same or is there a difference?
Me: Told him the difference between program and process and what all things will be included in program size. (He seemed to be less convinced)
P2: Started giving hints again, Does it have anything to do with how a program is allocated memory?
Me: Yes Sir, Told him about all the sections of memory where a program will reside.
P2: Take some basic C example and tell in which section that part of code will reside.
Me: Took a basic C example with global variable, local variable and pointers and explained which variable will be stored in each section.
P2: Some cross questioning was done on pointer variable storage and program and process size again.

Chairperson: You have written Software Engineering
P3: What are the topics you have studied in SE?
Me: Answered
P3: Take any SDLC model and explain the phases?
Me: Answered
P3: Limitations of waterfall, Why to use other models, Distinguishing features of other models - Prototyping, Spiral Model.
Me: Answered (and then some cross questioning on Prototyping Model)
P3: How unit testing is carried out? Functional Testing? 
Me: Answered
P3: What is done in System Testing? And the phases after Testing in SDLC?
Me: Answered
P3: How do you check whether the output of requirement phase is correct, what is going in the design phase is correct? The connection between Requirement Analysis and Design Phase.
Me: I could not really understand what exactly he was asking , he repeated it twice then I explained him about SRS, SDD, Verification and Validation but he was not convinced
Chairperson: I think you should look this thing up once you go back.
Moving her head towards right, Okay DBMS questions 

P4: Suppose we have 2 tables Employees and Department and I want to find the name of all employees whose salary is greater than the average salary of all the employees. First draw the ER diagram (He mentioned all the attributes in both the tables).
Me: Drawn
P4: What are the minimum number of tables required?
Me: 2 (based on the attributes he has given) and also showed him the Foreign key primary key relationship
P4: Okay, Now write the query?
Me: Answered
P4: Suppose I want to find the name of employees department wise whose salary is greater than the average salary of their department.
Me: Answered
P4: Some more things need to be added in this query because it will not run as it is, but that's okay.

Chairperson: Okay Badal come and sit on the chair. How was the interview? 
Me: It was good, I got confused in SE questions but I will look at them once I go back.
Chairperson: Did you study SE in your MTech?
Me: No Mam, I like to read about SE that's why I chose this subject.  
Then She started asking me from where I had come, For How long would I be staying in Mumbai, How I had reached here, How safe was my flight, What all things were given in the flight, Were they operating in full capacity. Then she said, I could go now and wished me luck for the result. I came out with a smile. The guy who was standing outside said that my interview lasted for 1 hour and 4 minutes.

Result :

I did not see my name in the final list but overall I had a wonderful experience. All the interviewers are very humble, even if you are nervous at start they will make you at ease or if you are stuck somewhere they will give you hints and require you to think and then apply your mind. I am sure the interview experience will be really great. Good luck to those who are appearing for it.

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