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GATE CS - Previous Year Questions

Previous-year GATE CS prompts for practice — options only until official keys are verified

142 questions15 pages~213 min

Practice with previous-year prompts and options. Official answer keys are not shown here yet — mark your choice, then verify against the IIT key PDF.

Use this track for exam reading speed and elimination practice until verified keys are linked.

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Page 8 of 15 • Questions 71-80 of 142

Practice mode: questions and options only. Official IIT answer keys are not linked here yet — mark your choice, then cross-check the official key yourself.

Q71medium

[GATE CS 2025 Set-2 Q52] Let Σ = {𝑎,𝑏,𝑐}. For 𝑥 ∈ Σ∗, and 𝛼 ∈ Σ, let # (𝑥) denote the number of 𝛼 occurrences of 𝛼 in 𝑥. Which one or more of the following option(s) define(s) regular language(s)?

A){𝑎𝑚𝑏𝑛 | 𝑚,𝑛 ≥ 0}

B){𝑎,𝑏}∗ ∩{𝑎𝑚𝑏𝑛𝑐𝑚−𝑛 | 𝑚 ≥ 𝑛 ≥ 0}

C){𝑤 | 𝑤 ∈ {𝑎,𝑏}∗,# (𝑤) ≡ 2 (mod 7),and # (𝑤) ≡ 3 (mod 9)} 𝑎 𝑏

D){𝑤 | 𝑤 ∈ {𝑎,𝑏}∗,# (𝑤) ≡ 2 (mod 7),and # (𝑤) = # (𝑤)} 𝑎 𝑎 𝑏

Q72medium

[GATE CS 2025 Set-2 Q53] Consider the database transactions T1 and T2, and data items X and Y. Which of the schedule(s) is/are conflict serializable? Transaction T1 Transaction T2 R1(X) W2(X) W1(Y) W2(Y) R1(X) COMMIT(T2) W1(X) COMMIT(T1)

A)R1(X), W2(X), W1(Y), W2(Y), R1(X), W1(X), COMMIT(T2), COMMIT(T1)

B)W2(X), R1(X), W2(Y), W1(Y), R1(X), COMMIT(T2), W1(X), COMMIT(T1)

C)R1(X), W1(Y), W2(X), W2(Y), R1(X), W1(X), COMMIT(T1), COMMIT(T2)

D)W2(X), R1(X), W1(Y), W2(Y), R1(X), COMMIT(T2), W1(X), COMMIT(T1)

Q73medium

[GATE CS 2025 Set-2 Q54] Consider the following relational schema: Students (rollno: integer, name: string, age: integer, cgpa: real) Courses (courseno: integer, cname: string, credits: integer) Enrolled (rollno: integer, courseno: integer, grade: string) Which of the following options is/are correct SQL query/queries to retrieve the names of the students enrolled in course number (i.e., courseno) 1470?

A)SELECT S.name FROM Students S WHERE EXISTS (SELECT * FROM Enrolled E WHERE E.courseno = 1470 AND E.rollno = S.rollno);

B)SELECT S.name FROM Students S WHERE SIZEOF (SELECT * FROM Enrolled E WHERE E.courseno = 1470 AND E.rollno = S.rollno) > 0;

C)SELECT S.name FROM Students S WHERE 0 < (SELECT COUNT(*) FROM Enrolled E WHERE E.courseno = 1470 AND E.rollno = S.rollno);

D)SELECT S.name FROM Students S NATURAL JOIN Enrolled E WHERE E.courseno = 1470;

Q74medium

[GATE CS 2024 Set-1 Q11] Let 𝑓:ℝ → ℝ be a function such that 𝑓(𝑥) = max{𝑥,𝑥3}, 𝑥 ∈ ℝ , where ℝ is the set of all real numbers. The set of all points where 𝑓(𝑥) is NOT differentiable is

A){−1,1,2}

B){−2,−1,1}

C){0,1}

D){−1,0,1} 1 2 3

Q75medium

[GATE CS 2024 Set-1 Q12] The product of all eigenvalues of the matrix [4 5 6] is 7 8 9

A)−1

B)0

C)1

D)2 Page 8 of 36 Organizing Institute: IISc Bengaluru Computer Science and Information Technology Set 1 (CS1)

Q76medium

[GATE CS 2024 Set-1 Q13] Consider a system that uses 5 bits for representing signed integers in 2’s complement format. In this system, two integers 𝐴 and 𝐵 are represented as 𝐴=01010 and 𝐵=11010. Which one of the following operations will result in either an arithmetic overflow or an arithmetic underflow?

A)𝐴+𝐵

B)𝐴−𝐵

C)𝐵 −𝐴

D)2∗𝐵

Q77medium

[GATE CS 2024 Set-1 Q14] Consider a permutation sampled uniformly at random from the set of all permutations of {1,2,3,⋯,𝑛} for some 𝑛 ≥ 4. Let 𝑋 be the event that 1 occurs before 2 in the permutation, and 𝑌 the event that 3 occurs before 4. Which one of the following statements is TRUE?

A)The events 𝑋 and 𝑌 are mutually exclusive

B)The events 𝑋 and 𝑌 are independent

C)Either event 𝑋 or 𝑌 must occur

D)Event 𝑋 is more likely than event 𝑌 Page 9 of 36 Organizing Institute: IISc Bengaluru Computer Science and Information Technology Set 1 (CS1)

Q78medium

[GATE CS 2024 Set-1 Q15] Which one of the following statements is FALSE? In the cycle stealing mode of DMA, one word of data is transferred between an I/O

A)device and main memory in a stolen cycle For bulk data transfer, the burst mode of DMA has a higher throughput than the

B)cycle stealing mode Programmed I/O mechanism has a better CPU utilization than the interrupt driven

C)I/O mechanism The CPU can start executing an interrupt service routine faster with vectored

D)interrupts than with non-vectored interrupts Page 10 of 36 Organizing Institute: IISc Bengaluru Computer Science and Information Technology Set 1 (CS1)

Q79medium

[GATE CS 2024 Set-1 Q16] A user starts browsing a webpage hosted at a remote server. The browser opens a single TCP connection to fetch the entire webpage from the server. The webpage consists of a top-level index page with multiple embedded image objects. Assume that all caches (e.g., DNS cache, browser cache) are all initially empty. The following packets leave the user’s computer in some order. (i) HTTP GET request for the index page (ii) DNS request to resolve the web server’s name to its IP address (iii) HTTP GET request for an image object (iv) TCP SYN to open a connection to the web server Which one of the following is the CORRECT chronological order (earliest in time to latest) of the packets leaving the computer ?

A)(iv), (ii), (iii), (i)

B)(ii), (iv), (iii), (i)

C)(ii), (iv), (i), (iii)

D)(iv), (ii), (i), (iii)

Q80medium

[GATE CS 2024 Set-1 Q17] Given an integer array of size N, we want to check if the array is sorted (in either ascending or descending order). An algorithm solves this problem by making a single pass through the array and comparing each element of the array only with its adjacent elements. The worst-case time complexity of this algorithm is

A)both Ο(𝑁) and Ω(𝑁)

B)Ο(𝑁) but not Ω(𝑁)

C)Ω(𝑁) but not Ο(𝑁)

D)neither Ο(𝑁) nor Ω(𝑁) Page 11 of 36 Organizing Institute: IISc Bengaluru Computer Science and Information Technology Set 1 (CS1)

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