GATE 2021 Computer Science (CS) Answer Key (Out) – Check Here for CS-1, 2

GATE 2021 Computer Science (CS) Answer Key – GATE CSE answer key 2021 is now available for session 1 and session 2. The answer key for Computer Science and Information Technology is available separately for Shift 1 and 2. Using the GATE 2021 Computer Science answer key, candidates can check their probable score. GATE 2021 CS answer key is to be used with the marking scheme of the exam. Know more details on GATE 2021 Computer Science (CS) Answer Key from this page.

Latest: GATE 2021 Computer Science (CS) answer key and question papers is out now. Check it below.

GATE 2021 Question Paper

Along with the answer key, IIT also uploads GATE question paper pdf. It is available for all 27 subjects of GATE, including the session 1 and 2 of the CS paper. The question paper of GATE 2021 contains all the questions for general aptitude and subject paper. The candidates can use the GATE question paper, answer key, and response sheet to evaluate their score in the exam.

SubjectQuestion Paper
Computer Science (CS -1)Check Here
Computer Science (CS -2)Check Here

Official GATE 2021 Computer Science (CS) Answer Key

The official GATE answer key is of two types:

  • Provisional answer key
  • Final answer key
SubjectAnswer Key
Computer Science (CS -1)Check Here
Computer Science (CS -1)Check Here

Provisional answer key – IITs release the provisional answer key after the exam. It is open for a challenge by the candidates.

Final answer key – The objections submitted against the provisional answer key are checked. As per all the valid challenges, changes and made in the answer key. The updated answer key is the final answer key. It is to be noted that the final key cannot be challenged. Further, as per the answers in the final answer key, result of GATE is evaluated.

How to Download Official GATE 2021 Computer Science (CS) Answer Key

Candidates can download the official answer key of GATE 2021 CS paper from this page. The answer key can also be downloaded from It is made available as PDF. While downloading the answer key, make sure to check the paper code. Here is how to download the answer key:

  • Go to, there is no need to login at GOAPS.
  • Next, locate the link for answer key of GATE 2021.
  • Then, locate the subject paper for which you appeared in GATE 2021.
  • After that, click on the answer key link corresponding to your subject paper name.
  • The answer key is downloaded in your system as PDF file.
  • Use the same to evaluate a probable score in the exam.

GATE 2021 CE Answer Key by Coaching Institutes

Various coaching institutes release the answer key for GATE 2021. Candidates can check and download it from below

CoachingGATE CS 1 Answer KeyGATE CS 2 Answer Key
The GATE AcademyCheck Here (Version 1) | Check here (Version 2)Check Here
Made EasyCheck HereCheck Here
GATE ForumCheck HereCheck Here

GATE 2021 Computer Science (CS) Answer Key

  • Exam Date – February 13, 2021
  • Time – 9.30 am to 12:30 pm | 3:00 pm to 6:00 pm
  • Subject Paper – Computer Science and Information Technology (CS)
  • GATE 2021 Result Date: 22 March 2021

If you appeared for GATE 2021 CS paper, then submit your questions and we will provide you the answer key. Click on the button below to submit answers. All the best!


Q1. Identify regular expression that generated all strings over Σ = {a, b} where number of a’s is divisible by 3.
Ans. b* (b*ab*ab*ab*)*b*

Q2. L1 is regular, L2 is CFL. Which of the following option is CFL?

Q3. Decimal equivalent of binary number is divisible by 3. Identify the regular expression.

Q4. P —–> QR
RS ——-> T
Which of the following FDs can be inferred?
A.) P —-> R
B.) P —–> S
C.) S —–> T
D.) P —–> Q
Ans. Correct option is [A and D]

Q5. Page size is given as 4KB and the page table entry is 8 B. Each virtual address is containing 39 bits and each physical address is given as 2 gigabytes. What is the memory required for storing the outermost page table?
Ans. 4KB

Q6. (0.1101)2 = (0.8xy5)10. Find the value of x +y.
Ans. 3

Q7. main ()
integer x;
return 0;
Which phase will generate an error?
A.) Synatx analysis
B.) Semantic analysis
C.) Machine depended
D.) Lexical error
Ans. Correct option is [A]

Q8. Which of the following is not intermediate representation?
A. Symbol table
B. Control flow graph
C. Abstract syntax tree
D. Three Address code
Ans. Correct option is [A]

Q9. (x-½)2 – (x-3/2)2 = x +2
Ans. 4

Q10. Consider a relation R./ which one of the following is /are true?
A: A relation must have atleast one foreign key.
B: Foreign key must not identify tuple.
Ans. Both are false

Q1. There are 4 DFAs. Which of the given DFA  is accepting all the strings ending with 011?

Q2. “Digital Logic (Number System) Q representation of a number in base 3 is 210. What is its hexadecimal representation?”

Q3. What are the maximum eigenvalues of 4*4 matrix with all diagonal elements are 0 and the rest is 1?
Ans. 3

Q4. Which C library function invokes system function call ()?
A.) strlen
b.) exit
c.) sleep
d.) malloc

Q5. A graph g contains 8 vertices and 5 faces. Find the number of edges?
Ans. 11

Q6. True or False?
A. The SLR (1) grammars are unambiguous and there are some unambiguous grammars that are not SLR (1).
B. There exist at most O(n-1) algorithm to parse the CFG grammars at
Ans. Both the statements are true

Q7. Consider 3 processes A, B, C all arrived at time zero with respective burst time 10, 20, 16. The average waiting time with non Preemptive SJF S.
Ans. 12

Q8. The main memory size is 232. The direct mapped cache of size 32 kb. Block size 64 bytes. What will be the tag length?
Ans. ​17

Q9. G is grouped with order 6. H is a subgroup of G. If 1 < |H| < 6. Then –
A. G is cyclic and H is also cyclic
B. G is not cyclin but H is cyclic
C. G is never cyclic also H is not cyclic
D. G is cyclic but H is not cyclic
Ans. Correct option is [B]

Q10. The question below consists of a pair of related words followed by four pairs of words. Select the pair that best expresses the relation in the original pair. Unemployed: Worker
(A) fallow: land
(B) unaware: sleeper
(C) wit: jester
(D) renovated: house

Q11. If the ratio of boys and girls in a class is 7:3.Then which of the values possibly the total number of students

Q12. We have two rectangular sheets of paper M and N of dimension 6 cm × 1cm each sheet is rolled to form an open cylinder by bringing two short edges of the sheet together. Sheet N is cut into equal square patches and assembled to form the largest possible closed cube. Assuming the ends of the cylinder are closed the ratio of the volume of the cylinder to that of the cube is

Q13. There are five bags each containing identical sets of ten distinct chocolates. One chocolate is picked from each bag probability that at least two chocolate is identical is __.

Q14. (i) Everybody in the class is prepared for the exam.
(ii) Baby invited Danish to his home because he enjoys playing chess
Which is a correct observation about the two
(A) (i) is grammatically correct (ii) is unambiguous
(B) (ii) grammatically correct (ii) ambiguous
(C) (i) grammatically incorrect (ii) ambiguous
(D) (i) grammatically incorrect (ii) unambiguous

Q15. ________ is to surgery as writer is to _________. Which of the following option maintains a similar logical relation in the above sentence.
(A) medicine, grammar
(B) hospital, library
(C) plan, outline
(D) doctor, books

Q16. Two hosts p and q transfer data with each other connected with a router r MTU from p to r is 1500 bytes and r to q is 800 bytes data send from p to q is 1400 bytes using TCP fragmentation happens.

Q17. A polygon is convex if, for every pair of points, P & Q belonging to the polygon. The line segment PQ lies completely inside or on the polygon. Which one of the following is not a convex polygon?

Q18. Static of cost of item P to cost of Q is 3: 4 discount is calculated as the difference between M.P & S.P. the profit percentage is calculated as the ratio of the difference between S.P and cost to the cost the discount on item Q, as a percentage of its marked price is ______.

Q19. Solve the recurrence relation:
T(N) = T(n/2) + T(2n/5) + 7n
Ans. nlogn

Q20. S1: Function calling sequence follows pre-order
S2: Function return follows post-order.
Which of the following is true?


Ans. 0.25

You can also check: GATE answer keys for all 27 papers | GATE 2021 CS paper analysis

The memory-based answer key for the GATE 2021 exam is available in various formats like image, video, PDF, etc. These answer keys are prepared based on the questions out of the memory of the GATE candidates. Hence the accuracy of these keys can be less, but they are enough for a rough score estimation.

GATE 2021 Computer Science (CS) Answer Key

The important dates for GATE 2021 answer key are as follows:

GATE 2021Dates
GATE 2021 exam dates06, 07, 13, 14 Feb 2021
GATE 2021 answer key26 Feb 2021
GATE result declaration22 Mar 2021
Last date to download scorecard31 May 2021

How to Calculate Score Using GATE 2021 Computer Science (CS) Answer Key?

To calculate score using GATE answer key, candidates can use the steps below:

Step 1: Download GATE 2021 answer key for your subject paper. Also, download the GATE 2021 response sheet and question paper of GATE 2021.

Step 2: Now, match the responses given in the answer from the response mentioned in the response sheet.

Step 3: Next, the candidates need to add or deduct marks, as per the marking scheme. It is as follows:

Type of questionsFor correct answerFor wrong answers
MCQs – 2 marks questionsadd 2 marksdeduct 2/3 marks
MCQs – 1 marks questionsadd 1 marksdeduct 2/3 marks
NATs – 2 marks questionsadd 2 marksno negative marking
NATs – 1 marks questionsadd 1 marksno negative marking
MSQs – 2 marks questionsadd 2 marksno negative marking
MSQs – 1 marks questionsadd 1 marksno negative marking

Step 4: When marks are added or deduct for all the questions, candidates get their estimated score of GATE.

GATE Computer Science and Information Technology (CS) Paper Cut Off

In GATE, each paper has a different cutoff, you can check below the cutoff score or the minimum marks that you need in CS to pass it. The cutoff marks for this year shall be available with the declaration of the GATE 2021 result.

YearGATE CS paper cutoff
GATE CS paper cutoff
GATE CS paper cutoff
(SC / ST / PwD)

GATE 2021 Result

After the closing of the Contest window, the exam conducting body releases a final answer key on the basis of which the scorecard (result) is prepared. The candidates can check their GATE 2021 result / scorecard with their marks and an all India rank through the login at the official GOAPS website. The candidates can download their GATE 2021 result on the scheduled date.

Note: The Scorecard is valid for a period of three years from the date of the declaration of the results.

GATE 2021

GATE 2021 is held at a national level and in online mode. One of the IITs conducts this exam on a rotational basis. GATE 2021 is conducted by IIT Bombay. Also, the score of GATE 2021 is also used by many PSUs for recruitment. Qualifiers of the exam get admission in master’s programs and direct Doctoral programs in engineering/technology/architecture and doctoral programs in relevant branches of science.

GATE 2021 Computer Science (CS) Answer Key FAQs

If the official GATE Answer Key has a wrong answer, and it is corrected by the authorities, will all the candidates get the marks?

Yes, if the exam conducting body finds adequate proof against any wrong question, they then release a corrected answer key.

What does “Marks to All” in GATE official answer key mean?

The term “Marks to All” in the GATE official answer key means that all the candidates will get the marks for that particular question irrespective of them attempting the question because the question was either ambiguous, incomplete or wrong in the question paper itself.

How can I calculate my Score using the GATE 2021 Answer Key?

The candidates can use the Answer Key to determine the number of correct answers attempted by them in the GATE 2021 exam, and by using the official marking scheme, you can get an estimated score of the exam.

 Is there any difference between the Official and the Unofficial GATE Answer Key?

Yes, official and Unofficial Answer Key are different. At times, the coaching institutes that publish the Unofficial versions of the Answer Key may not know the complete question or there might be certain discrepancy due to ambiguous questions, the answers may differ. However, the candidates must note that only the Official Answer Key is used for evaluating GATE results.

Official website:

Engineering Entrance Exam Application Tracker

Last Date Exam Registration
25-Apr-21 SNU Apply Now!!
30-Apr-21 LPUNEST Apply Now!!
Apr-2021 AEEE Apply Now!!
Apr-2021 NIIT University Apply Now!!
Apr-2021 VITEEE Apply Now!!
09-May-21 VTUEEE Apply Now!!
29-May-21 CUCET Apply Now!!
02-May-21 Amrita M.Tech Apply Now!!
31-May-21 SRMJEEE Apply Now!!
31-May-21 KIITEE Apply Now!!
31-May-21 SAAT Apply Now!!
31-May-21 Sharda University Apply Now!!
04-Jun-21 Symbiosis SET Apply Now!!
05-Jun-21 HITSEEE Apply Now!!
10-Jun-21 UPESEAT Apply Now!!
15-Jun-21 GD Goenka Apply Now!!
15-Jun-21 Manav Rachna Apply Now!!
17-Jun-21 PESSAT Apply Now!!
20-Jun-21 BVP CET Apply Now!!
30-Jun-21 Jain University Apply Now!!
30-Jun-21 DIT University Apply Now!!
30-Jun-21 BML Munjal Apply Now!!
30-Jun-21 JLU Apply Now!!
30-Jun-21 UEM Jaipur Apply Now!!
30-Jun-21 UEM Kolkata Apply Now!!

Leave a Reply

GD Goenka University 2021 Apply Now!!