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GATE CSE 2020 question paper with answers

Official paper organised by IIT Delhi: 65 questions, 100 marks. Every answer is from the official final answer key. Open any question to try it, see the answer and the concept behind it.

Practise this paper free →Official question paper (PDF)Official answer key (PDF)

General Aptitude (Q1–Q10)

  1. Q1Prepositions: confident of speaking English ___ six monthsGeneral Aptitude1M · MCQAns: D
  2. Q2Contrast after "but": excellent knowledge, classroom performance was ___General Aptitude1M · MCQAns: A
  3. Q3Analogy: Cook : Cook :: Fly : ?General Aptitude1M · MCQAns: A
  4. Q4Inference from a passage on melting glaciers and emissionsGeneral Aptitude1M · MCQAns: D
  5. Q5Cheapest route through a network with edge costs and tollsGeneral Aptitude1M · MCQAns: B
  6. Q6Inference from a passage on GSTGeneral Aptitude2M · MCQAns: D
  7. Q7Letter values: P = 3, R = 27, T = 243, find Q + SGeneral Aptitude2M · MCQAns: C
  8. Q8Unpainted area of an annulus filled with touching circlesGeneral Aptitude2M · MCQAns: A
  9. Q9Sum of acute angles of two perpendicular lines with the X-axisGeneral Aptitude2M · MCQAns: B
  10. Q10Aggregate profit or loss from a revenue bar graphGeneral Aptitude2M · MCQAns: C

Computer Science and Information Technology (Q11–Q65)

  1. Q11Which functions are increasing everywhere in [0, 1]Engineering Mathematics1M · MCQAns: A
  2. Q12Solve T(n) = T(n^(1/a)) + 1 with T(b) = 1Algorithms1M · MCQAns: A
  3. Q13True statements about interrupts, polling and DMAComputer Organization and Architecture1M · MCQAns: C
  4. Q14Order of micro-steps for R0 ← R1 + R2 on a single-bus datapathComputer Organization and Architecture1M · MCQAns: C
  5. Q15Postorder of a BST from its preorder 15, 10, 12, 11, 20, 18, 16, 19Programming and Data Structures1M · MCQAns: B
  6. Q16Worst-case time to insert n^2 elements into an AVL tree of nProgramming and Data Structures1M · MCQAns: C
  7. Q17Regular expression for binary strings with an odd number of 1sTheory of Computation1M · MCQAns: Marks to all
  8. Q18Regularity of a union and closure under infinite unionTheory of Computation1M · MCQAns: D
  9. Q19Symbol table use, heap for recursion, declare-before-use errorsCompiler Design1M · MCQAns: D
  10. Q20Is {a^n} ∪ {a^n b^n} deterministic context-free or LL(k)?Theory of Computation1M · MCQAns: C
  11. Q21Comparing leftover holes for first, next, best and worst fitOperating System1M · MCQAns: C
  12. Q22Valid process state transitions under preemptive schedulingOperating System1M · MCQAns: C
  13. Q23Rows returned by a join with a nested AVG subqueryDatabases1M · MCQAns: A
  14. Q24ER notation for the identifying relationship of a weak entityDatabases1M · MCQAns: A
  15. Q25True statements about an IP router's forwarding behaviourComputer Networks1M · MCQAns: D
  16. Q26Worst-case time to build a sorted linked list by n insertionsProgramming and Data Structures1M · MCQAns: C
  17. Q27Probability that a random relation on {1,2,3} is reflexiveEngineering Mathematics1M · NATAns: 0.125
  18. Q28Largest proper subgroup of a group of order 35Engineering Mathematics1M · NATAns: 7
  19. Q29Select lines for a multiplexer choosing one of 32 registersDigital Logic1M · NATAns: 5
  20. Q30Decoder inputs plus outputs for a byte-addressable 1 KB RAMDigital Logic1M · NATAns: 1034
  21. Q31Average access time of a direct-mapped cache with word-wise refillComputer Organization and Architecture1M · NATAns: 13.3 (or 13.5)
  22. Q32Output of pointer arithmetic on a 2D array: *(*(a+**a+2)+3)Programming and Data Structures1M · NATAns: 19
  23. Q33Probe 1 address under double hashing for key 90Programming and Data Structures1M · NATAns: 13
  24. Q34Reduction steps of a bottom-up parse of aaadbbbCompiler Design1M · NATAns: 7
  25. Q35TCP connections to load a page with five images, non-persistent HTTPComputer Networks1M · NATAns: 6
  26. Q36Which Turing machine languages are undecidableTheory of Computation2M · MCQAns: A
  27. Q37Rank and determinant identities for products and sumsEngineering Mathematics2M · MCQAns: C
  28. Q38Minterm list of z = a OR (NOT b AND c) from a gate circuitDigital Logic2M · MCQAns: B
  29. Q39IEEE-754 single precision division 0x42200000 / 0xC1200000Computer Organization and Architecture2M · MCQAns: B
  30. Q40Which addresses map to the same set in a 4-way set-associative cacheComputer Organization and Architecture2M · MCQAns: B
  31. Q41Checking whether an MST survives the addition of one edgeAlgorithms2M · MCQAns: D
  32. Q42Classify L1 = {wxyx} and L2 = {xy : |x| = |y|, x ≠ y}Theory of Computation2M · MCQAns: A
  33. Q43Which semantic rules are L-attributedCompiler Design2M · MCQAns: B
  34. Q44What a semaphore barrier between code sections P and Q achievesOperating System2M · MCQAns: A
  35. Q45False statement about an SSTF disk schedule from cylinder 100Operating System2M · MCQAns: B
  36. Q46What must hold for a relation in 3NF but not in BCNFDatabases2M · MCQAns: A
  37. Q47Schedule conflict equivalent to a given two-transaction scheduleDatabases2M · MCQAns: A
  38. Q48Candidate /21 blocks from 202.61.0.0/17 for 1500 hostsComputer Networks2M · MCQAns: B
  39. Q49Which quantifier equivalence with a closed formula W is not validEngineering Mathematics2M · MCQAns: C
  40. Q50Shortest paths under the reweighting w'(u,v) = w(u,v) + f(u) − f(v)Algorithms2M · MCQAns: A
  41. Q51Range reporting in a balanced BST with k resultsProgramming and Data Structures2M · MCQAns: B
  42. Q52Derangements of LILAC with the two L's identicalEngineering Mathematics2M · NATAns: 12
  43. Q53Speedup of a 5-stage pipeline with memory and branch stallsComputer Organization and Architecture2M · NATAns: 2.15 to 2.18
  44. Q54Maximum R-type opcodes with expanding opcodes in a 16-bit formatComputer Organization and Architecture2M · NATAns: 14
  45. Q55Probability that a·x is odd for a random binary vector xEngineering Mathematics2M · NATAns: 0.5
  46. Q56Return value of fun2(5) with static variables in recursionProgramming and Data Structures2M · NATAns: 55
  47. Q57Comparisons to find the maximum in a min-heap of 1023 elementsProgramming and Data Structures2M · NATAns: 511
  48. Q58Value of pp(3, 4) for binary exponentiation codeProgramming and Data Structures2M · NATAns: 81
  49. Q59MST weight of a complete graph with weights |i − j|Algorithms2M · NATAns: 99
  50. Q60Difference of average turnaround times for SJF and RR (q = 4)Operating System2M · NATAns: 5.25
  51. Q61Minimum DFA states: number of a's divisible by 2 but not by 3Theory of Computation2M · NATAns: 6
  52. Q62Edge chromatic number of K(3,4) plus a vertex joined to allEngineering Mathematics2M · NATAns: 7
  53. Q63Effective memory access time with TLB, page faults and dirty pagesOperating System2M · NATAns: 154.5 to 155.5
  54. Q64Disk accesses to fetch a record via a B+ tree of one million keysDatabases2M · NATAns: 4
  55. Q65TCP congestion window after 60 ms with slow start and AIMDComputer Networks2M · NATAns: 44