Topic MCQs — Operating Systems & Linux

30 questions · DSSSB TGT CS style · Original

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Q1. Which is NOT a typical OS function?

• A) Process management
• B) Compiling high-level language by default as CPU firmware
• C) Memory management
• D) File management Answer: B
  OS manages resources; language compilers are separate tools.

Q2. In multiprogramming:

• A) Only one program may reside in memory
• B) Multiple programs reside in memory to improve CPU utilization
• C) Multiple CPUs are mandatory
• D) No I/O is allowed Answer: B
  CPU can switch to another job when one waits for I/O.

Q3. Time-sharing OS emphasizes:

• A) Batch punch cards only
• B) Interactive time slices among users/processes
• C) No scheduling
• D) Only real-time hard deadlines always Answer: B
  Time-sharing provides interactive multitasking via slices.

Q4. A real-time OS is critical when:

• A) Deadlines must be met (hard/soft)
• B) Only printing banners
• C) No interrupts exist
• D) Disk is optional always Answer: A
  RTOS correctness includes timely response.

Q5. Valid process state transition is:

• A) Waiting → Running directly always without Ready
• B) Ready → Running via dispatch
• C) New → Terminated only path
• D) Running → New Answer: B
  Scheduler dispatches a ready process to running.

Q6. PCB stands for:

• A) Process Control Block
• B) Primary Cache Buffer
• C) Program Compiler Base
• D) Peripheral Cable Bus Answer: A
  PCB stores process metadata for the kernel.

Q7. FCFS scheduling can suffer from:

• A) Belady’s anomaly only
• B) Convoy effect
• C) Mandatory preemption every 1 ms
• D) No waiting time ever Answer: B
  Long job at head delays short jobs (convoy).

Q8. SJF scheduling selects:

• A) Longest job first
• B) Shortest CPU burst next
• C) Random job
• D) Only I/O-bound last Answer: B
  Shortest Job First minimizes average waiting (with known bursts).

Q9. Round Robin is characterized by:

• A) No time quantum
• B) Fixed time quantum and preemption
• C) Always optimal average wait like SJF
• D) Non-preemptive only Answer: B
  RR cycles processes with quantum q.

Q10. Priority scheduling may cause:

• A) Guaranteed no waiting
• B) Starvation of low-priority processes
• C) Elimination of PCB
• D) No context switches Answer: B
  Aging is used to counter starvation.

Q11. Which is a necessary condition for deadlock?

• A) Spooling
• B) Circular wait
• C) Paging
• D) Time quantum Answer: B
  Coffman: mutual exclusion, hold-and-wait, no preemption, circular wait.

Q12. Banker's algorithm is used for:

• A) Disk formatting
• B) Deadlock avoidance via safe-state check
• C) Compiling C programs
• D) DNS resolution Answer: B
  Allocates resources only if a safe sequence remains.

Q13. Paging divides:

• A) Processes into variable segments only
• B) Address space into fixed-size pages mapped to frames
• C) Files into directories only
• D) CPU into cores by OS UI Answer: B
  Pages ↔ frames; reduces external fragmentation.

Q14. Thrashing means:

• A) CPU overheating only
• B) Excessive paging with little productive work
• C) Fast cache hits always
• D) Deadlock among printers only Answer: B
  System spends most time swapping pages.

Q15. LRU page replacement replaces:

• A) Most recently used page
• B) Least recently used page
• C) Random page always
• D) Only page 0 Answer: B
  LRU approximates optimal by recency.

Q16. OPT (optimal) page replacement:

• A) Is always practically implementable with free future knowledge
• B) Replaces the page used farthest in the future
• C) Is identical to FIFO always
• D) Never used as a benchmark Answer: B
  OPT is a theoretical benchmark needing the future reference string.

Q17. Belady’s anomaly is associated notably with:

• A) LRU
• B) FIFO
• C) OPT
• D) Round Robin CPU only Answer: B
  FIFO may fault more with more frames.

Q18. In Linux, the kernel is:

• A) Only a text editor
• B) Core that manages hardware, processes, memory
• C) A spreadsheet
• D) Only the GUI theme Answer: B
  Kernel is the OS core; shell is the command interface.

Q19. Command pwd displays:

• A) Password database
• B) Present working directory
• C) Process wait delay
• D) Printer device Answer: B
  Print Working Directory.

Q20. Absolute path in Linux:

• A) Starts from current directory only
• B) Starts from root /
• C) Cannot include folders
• D) Is only ~Answer: B
  e.g. /home/user/file.txt.

Q21. chmod is used to:

• A) Change file permissions
• B) Change hostname only
• C) Compile modules
• D) Kill all processes Answer: A
  Mode bits rwx for user/group/others.

Q22. grep is used to:

• A) Partition disks
• B) Search text patterns in files
• C) Create users only
• D) Mount NFS only Answer: B
  Pattern search utility.

Q23. ps command shows:

• A) Packet statistics of Wi-Fi only
• B) Process status
• C) Printer spool only
• D) Python syntax Answer: B
  Lists processes; often paired with kill.

Q24. The root user in Linux:

• A) Has UID 0 and superuser privileges
• B) Cannot change permissions
• C) Is the same as directory .
• D) Exists only on Windows Answer: A
  Superuser account; home often /root.

Q25. Multiprocessing means:

• A) Many programs in memory on one CPU only
• B) Using multiple CPUs/cores
• C) Only batch tapes
• D) No concurrency Answer: B
  Distinguish from multiprogramming (many jobs in memory).

Q26. Virtual memory allows:

• A) Process address space larger than physical RAM (via secondary storage)
• B) Only ROM execution
• C) Disabling page tables always
• D) Removing all disks Answer: A
  Pages swapped between RAM and disk.

Q27. mv command:

• A) Only deletes files
• B) Moves or renames files/directories
• C) Makes virtual memory
• D) Mounts volumes only Answer: B
  Move/rename.

Q28. Segmentation as memory scheme:

• A) Uses only fixed-size blocks identical to pages
• B) Divides programs into logical variable-sized segments
• C) Is identical to RR scheduling
• D) Removes need for addresses Answer: B
  Code/data/stack segments etc.

Q29. Which scheduling is non-preemptive by classic definition?

• A) Round Robin
• B) FCFS
• C) SRTF
• D) Preemptive priority always Answer: B
  FCFS runs until block/finish (non-preemptive).

Q30. cat file.txt typically:

• A) Displays/concatenates file contents
• B) Changes ownership
• C) Creates a process namespace
• D) Compresses with gzip only Answer: A
  cat prints file(s) to standard output.