WB JECA MCA Operating System Previous Year Question Paper and Solution with PDF

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WB JECA MCA Previous Year Questions (PYQs)

WB JECA MCA Operating System PYQ

Qus : 1 WB JECA MCA PYQ

Each stage in pipelining should be completed within _________cycles.

(A) 1

(b) 2

(D) 4

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

In pipelining, the CPU instruction is divided into stages (Fetch, Decode, Execute, etc.).
To maximize throughput, each stage must complete within 1 clock cycle.
This ensures that new instructions can enter the pipeline without delay.

Correct Answer: (A) 1

Qus : 2 WB JECA MCA PYQ

A computer with a 32 bit wide data bus uses 4k × 8 static RAM memory chips. The smallest memory this computer is

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Solution

Each RAM chip = $4k \times 8 = 32k$ bits = 4 KB.
Bus width = 32 bits, each chip = 8 bits → need 4 chips in parallel.
Total memory = $4 \times 4$ KB = 16 KB.
Answer = (B) 16 kb

Qus : 3 WB JECA MCA PYQ

The permission -rwx r-- r-- represented in octal expression will be

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: Owner rwx = 7, group r-- = 4, others r-- = 4 ⇒ 744.
Answer: (B) 744

Qus : 4 WB JECA MCA PYQ

Which command changes a file's group owner?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: The Unix command to change a file's group is chgrp (change group).
Answer: (D) chgrp

Qus : 5 WB JECA MCA PYQ

Which of the following is/are not shared by threads?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: Threads share code, data, and OS resources, but each thread has its own stack and program counter.
Answer: (C) Both program counter and stack

Qus : 6 WB JECA MCA PYQ

Which one of the following is a synchronization tool?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: Semaphore is used for process synchronization, unlike pipe/socket/thread.
Answer: (C) Semaphore

Qus : 7 WB JECA MCA PYQ

When a process is in a "Blocked" state waiting for some I/O service, once completed it goes to the ____.

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Solution

Solution: A blocked process (waiting for I/O) goes to the Ready state after I/O is completed.
Answer: (D) Ready state

Qus : 8 WB JECA MCA PYQ

A process is thrashing if ____.

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Solution

Solution: Thrashing occurs when the CPU spends most of its time handling page faults rather than executing instructions.
Answer: (B) it spends more time in paging, rather than in execution

Qus : 9 WB JECA MCA PYQ

Which one of the following is deadlock avoidance algorithm ?

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Solution

Solution: Banker's algorithm checks for safe state to avoid deadlocks.
Answer: (B)

Qus : 10 WB JECA MCA PYQ

Which command is used to set the three permissions for all the three categories of users of a file ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: chmod sets read/write/execute bits for user, group, others (e.g., chmod 744 file).
Answer: (C) chmod

Qus : 11 WB JECA MCA PYQ

Which command is used for printing the current working directory ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: The Unix command to print the current directory is pwd.
Answer: (D) pwd

Qus : 12 WB JECA MCA PYQ

When several processes access the same data concurrently and the outcome depends on the particular order in which the access takes place is called ________.

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Solution

Solution: Order-dependent outcomes from concurrent access is a classic race condition.
Answer: (A) Race condition

Qus : 13 WB JECA MCA PYQ

Which option will be used with sort command to start sorting after the n-th column of the (m+1)th field ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: The Unix sort option to specify starting column is +m -n.
Answer: (B)

Qus : 14 WB JECA MCA PYQ

Which command is used for displaying the beginning of a file in Unix ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: The head command displays first lines of a file.
Answer: (D)

Qus : 15 WB JECA MCA PYQ

Three CPU-intensive processes (10, 20, 30 units) arrive at 0,2,6 respectively. Using shortest remaining time first scheduling, how many context switches are needed (excluding t=0 and end)?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: SRTF will preempt at arrivals (P1→P2 at t=2, P2→P3 at t=6). Thus 2 context switches occur.
Answer: (B) 2

Qus : 16 WB JECA MCA PYQ

Which command is used to extract specific columns from the file ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: The cut command extracts columns/fields from text files.
Answer: (B)

Qus : 17 WB JECA MCA PYQ

Which of the following is not a communication command ?

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Solution

Solution: grep is for searching text, not communication.
Answer: (D)

Qus : 18 WB JECA MCA PYQ

A deadlock avoidance algorithm dynamically examines the ____ to ensure circular wait never exists.

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Solution

Solution: Deadlock avoidance (e.g., Banker's) examines the resource allocation state.
Answer: (D)

Qus : 19 WB JECA MCA PYQ

Virtual memory is normally implemented by ____.

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2024 PYQ

Solution

Solution: Virtual memory is usually implemented using demand paging.
Answer: (A)

Qus : 20 WB JECA MCA PYQ

14. _________ is the most appropriate scheduling in case of a time-shared operating system.

(A) FCFS (B) RR (C) SJF (D) SRTF

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: Time-sharing systems aim for responsiveness and fairness, which is best provided by Round Robin (RR) using time quanta.

Qus : 21 WB JECA MCA PYQ

15. If only one process can be able to access a particular resource at a time, then it is known as ______________.

(A) Mutual execution (B) Mutual exclusion (C) Multiple execution (D) Multiple exclusion

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Solution

Explanation: Allowing only one process to access a resource at a time is called mutual exclusion (mutex).

Qus : 22 WB JECA MCA PYQ

16. Resource allocation graph is used to represent ______________.

(A) deadlock (B) virtual memory (C) main memory (D) scheduling

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: Resource Allocation Graph (RAG) models processes and resources; cycles in certain cases indicate deadlock.

Qus : 23 WB JECA MCA PYQ

17. Banker’s algorithm for resource allocation deals with ______________.

(A) mutual exclusion (B) mutual inclusion (C) deadlock recovery (D) deadlock avoidance

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: Banker’s algorithm is a deadlock avoidance algorithm ensuring the system stays in a safe state.

Qus : 24 WB JECA MCA PYQ

18. Page fault means ______________.

(A) required page is available in main memory (B) required page is not available in main memory (C) segment number (D) reduce page I/O

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: A page fault occurs when the referenced page is not present in main memory, forcing a page-in from secondary storage.

Qus : 25 WB JECA MCA PYQ

19. ___________ is a technique to move a process from main memory to secondary memory.

(A) Deadlock (B) Synchronization (C) Caching (D) Swapping

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: Swapping transfers processes between main memory and secondary storage to manage memory pressure.

Qus : 26 WB JECA MCA PYQ

20. Demand paging is considered as ______________.

(A) fetching a page when not needed (B) switching between two processes (C) fetching a page only when needed (D) switching between two threads

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: In demand paging, a page is loaded into memory only when it is actually referenced.

Qus : 27 WB JECA MCA PYQ

21. Thrashing means a condition having ______________.

(A) minimum paging (B) optimized paging (C) synchronized paging (D) excessive paging

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: Thrashing occurs when the system spends most time paging due to insufficient frames, causing excessive paging and poor performance.

Qus : 28 WB JECA MCA PYQ

22. A counting semaphore is initialized to 15. Then, 4 wait operations and 2 signal operations are completed on this semaphore. The resulting value of the semaphore is ____________.

(A) 11 (B) 13 (C) 17 (D) 19

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Solution

Explanation: Each wait (P) decrements; each signal (V) increments. Initial: 15 → after 4 waits: 11 → after 2 signals: 13. $$ 15 - 4 + 2 = 13 $$

Qus : 29 WB JECA MCA PYQ

23. What do you mean by fork()? Choose the correct option.

(A) Starvation (B) Creation of new task (C) Demand paging (D) Semaphore

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: fork() creates a new process (child) as a copy of the calling process.

Qus : 30 WB JECA MCA PYQ

24. In file management, FAT means ______________.

(A) Feature Access Table (B) File Access Table (C) Fault Allocation Table (D) File Allocation Table

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

Explanation: FAT stands for File Allocation Table, a file system layout used to map files to disk clusters.

Qus : 31 WB JECA MCA PYQ

33.In shell script, which command is used to create a new directory ?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

mkdir is the command to create a new directory in Unix/Linux.

Qus : 32 WB JECA MCA PYQ

34.In shell script, which command is used to copy a file?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

cp is used to copy files or directories in Unix/Linux.

Qus : 33 WB JECA MCA PYQ

35.In shell script, which command is used to delete a file?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

rm is the command to remove/delete files in Unix/Linux.

Qus : 34 WB JECA MCA PYQ

36.In Unix/Linux platform, which command is used to find out the difference between two files?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

diff compares two files line by line and shows differences.

Qus : 35 WB JECA MCA PYQ

37.In Unix/Linux platform, which command is used to create a symbolic link?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

ln -s is used to create symbolic (soft) links in Linux.

Qus : 36 WB JECA MCA PYQ

38.In Unix/Linux platform, which command is used to view the inode number of a file?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

ls -i displays the inode number of each file.

Qus : 37 WB JECA MCA PYQ

39.In Unix/Linux platform, which command is used to specify the access mode for files?

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WB JECA MCA Previous Year PYQ WB JECA MCA JECA MCA 2023 PYQ

Solution

chmod is used to change file permissions (read/write/execute).

Qus : 38 WB JECA MCA PYQ

40.In Unix/Linux platform, ______ command is used to show current running processes.

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Solution

ps shows the list of currently running processes.

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WB JECA MCA Previous Year Questions (PYQs)

WB JECA MCA Operating System PYQ

Solution

In pipelining, the CPU instruction is divided into stages (Fetch, Decode, Execute, etc.).To maximize throughput, each stage must complete within 1 clock cycle.This ensures that new instructions can enter the pipeline without delay.

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In pipelining, the CPU instruction is divided into stages (Fetch, Decode, Execute, etc.).
To maximize throughput, each stage must complete within 1 clock cycle.
This ensures that new instructions can enter the pipeline without delay.