21. What is the primary purpose of a shell in an OS?
- a) Acts as a command-line interpreter
- b) Manages hardware drivers
- c) Allocates CPU time
- d) Handles file encryption
Answer: A - The shell processes user commands and interacts with the kernel (e.g., Bash in Linux).
22. Which of these is a microkernel architecture?
- a) QNX
- b) Windows NT
- c) Linux
- d) macOS
Answer: A - QNX uses a microkernel where only essential services run in kernel space.
23. What is a race condition?
- a) Unpredictable behavior when processes access shared data concurrently
- b) A CPU overheating issue
- c) Disk fragmentation
- d) Network packet collision
Answer: A - Race conditions occur when outputs depend on the timing of uncontrollable events.
24. Which algorithm is used to avoid deadlocks?
- a) Banker's algorithm
- b) Round-robin algorithm
- c) Shortest-job-first
- d) FIFO
Answer: A - Banker's algorithm prevents deadlocks by checking resource allocation safety.
25. What does CPU burst time refer to?
- a) Time a process uses the CPU before I/O wait
- b) Total execution time of a program
- c) Time to load a process into memory
- d) CPU overheating duration
Answer: A - Burst time is critical for scheduling algorithms like SJF.
26. Which Windows tool monitors system performance?
- a) Performance Monitor
- b) Device Manager
- c) Disk Cleanup
- d) Registry Editor
Answer: A - Performance Monitor (perfmon) tracks CPU, memory, and disk usage.
27. What is the purpose of the 'fork()' system call?
- a) Creates a new process
- b) Allocates memory
- c) Opens a file
- d) Terminates a process
Answer: A - fork() duplicates the calling process (parent-child relationship).
28. Which Linux command changes file permissions?
- a) chmod
- b) chown
- c) ps
- d) grep
Answer: A - chmod modifies read/write/execute permissions (e.g., chmod 755 file).
29. What is a monolithic kernel?
- a) Kernel where all OS services run in kernel space
- b) A kernel with only basic functions
- c) A cloud-based kernel
- d) A kernel that supports only one user
Answer: A - Linux uses a monolithic kernel for high performance.
30. Which of these is a disk scheduling algorithm?
- a) SCAN (Elevator Algorithm)
- b) FIFO
- c) Round Robin
- d) Priority Scheduling
Answer: A - SCAN moves the disk arm back and forth like an elevator.
31. What is swap space used for?
- a) Extending virtual memory using disk storage
- b) Storing BIOS settings
- c) Caching web pages
- d) Backing up files
Answer: A - Swap space holds inactive memory pages when RAM is full.
32. Which Windows feature allows running Linux binaries?
- a) WSL (Windows Subsystem for Linux)
- b) Hyper-V
- c) PowerShell
- d) DirectX
Answer: A - WSL enables native Linux executable support on Windows.
33. What is the role of the 'init' process in Linux?
- a) First process (PID 1) that starts all other processes
- b) Manages network connections
- c) Handles graphical login
- d) Updates system packages
Answer: A - init (or systemd in modern systems) is the ancestor of all processes.
34. Which of these is a distributed operating system?
- a) Amoeba
- b) Windows 10
- c) Ubuntu
- d) Android
Answer: A - Amoeba OS provides a single-system image across multiple machines.
35. What is fragmentation in memory management?
- a) Free memory broken into small, non-contiguous blocks
- b) Corruption of system files
- c) Duplication of processes
- d) Overwriting of RAM data
Answer: A - Fragmentation reduces memory utilization efficiency.
36. Which command lists directory contents in Linux?
- a) ls
- b) cd
- c) pwd
- d) cat
Answer: A - ls displays files/folders (use ls -l for details).
37. What is a semaphore used for?
- a) Process synchronization
- b) Memory allocation
- c) Disk partitioning
- d) File compression
Answer: A - Semaphores control access to shared resources to prevent race conditions.
38. Which Windows version introduced the NT kernel?
- a) Windows NT 3.1 (1993)
- b) Windows 95
- c) Windows XP
- d) Windows 7
Answer: A - The NT kernel became the foundation for all modern Windows versions.
39. What does IPC stand for?
- a) Inter-Process Communication
- b) Internet Protocol Configuration
- c) Integrated Peripheral Controller
- d) Input Process Cycle
Answer: A - IPC includes methods like pipes, shared memory, and message queues.
40. Which Linux command searches for text patterns in files?
- a) grep
- b) find
- c) locate
- d) awk
Answer: A - grep "pattern" file.txt filters matching lines.