Questions: Operating Systems

Question 1: What is the primary function of an operating system?

A To manage hardware resources and provide services to applications
B To design computer hardware circuits
C To create programming languages exclusively
D To manufacture computer processors

Explanation: An operating system manages hardware resources, provides services to applications, and enables users to interact with a computer system.

Question 2: Which of the following is an example of an open-source operating system?

A Microsoft Windows
B macOS
C Linux
D Microsoft Excel

Explanation: Linux is an open-source operating system whose source code can be inspected, modified, and distributed under its applicable licenses.

Question 3: What is a process in an operating system?

A A file stored permanently on a hard drive
B A program in execution
C A physical component of the CPU
D A collection of computer networks

Explanation: A process is a program in execution, together with its execution state, allocated resources, and associated operating system information.

Question 4: Which scheduling algorithm allocates CPU time to processes in fixed time slices?

A First-Come, First-Served
B Shortest Job First
C Priority Scheduling
D Round Robin

Explanation: Round Robin scheduling assigns each ready process a fixed time quantum. If a process does not finish within its quantum, it is moved to the end of the ready queue.

Question 5: What is the main purpose of virtual memory?

A To increase the physical clock speed of the CPU
B To eliminate the need for secondary storage
C To provide processes with virtual address spaces and support memory use beyond physical RAM
D To prevent all application errors

Explanation: Virtual memory allows processes to use virtual address spaces that can exceed the available physical RAM by keeping selected data on secondary storage and bringing it into memory when needed.

Question 6: Which of the following is a necessary condition for deadlock?

A Unlimited resource availability
B Mutual exclusion
C Guaranteed process termination
D Automatic CPU overclocking

Explanation: Mutual exclusion is one of the four Coffman conditions for deadlock. The other three are hold and wait, no preemption, and circular wait.

Question 7: What is a context switch?

A The process of permanently deleting a program
B The conversion of source code into machine code
C The replacement of a computer's operating system
D Saving one process's execution state and restoring another's

Explanation: A context switch occurs when the operating system saves the execution state of one process or thread and restores the state of another so that execution can continue.

Question 8: Which memory management technique divides logical memory into fixed-size blocks called pages?

A Paging
B Segmentation only
C Disk formatting
D CPU pipelining

Explanation: Paging divides a process's virtual address space into fixed-size pages and physical memory into corresponding fixed-size frames. Pages can be mapped to available frames without requiring contiguous physical memory.

Question 9: What is the primary role of a device driver?

A To compile every application on the computer
B To replace the system's file system
C To enable the operating system to communicate with hardware devices
D To create user passwords automatically

Explanation: A device driver enables the operating system to communicate with and control a particular hardware device through its supported interface.

Question 10: Which of the following best describes a thread?

A A separate physical processor installed on the motherboard
B A unit of execution within a process
C A permanent storage partition
D A type of network cable

Explanation: A thread is an execution unit within a process. Threads in the same process typically share its address space and process resources, while maintaining their own execution state and stack.

Question 11: What is the main purpose of a semaphore in concurrent programming?

A To increase the capacity of the hard drive
B To translate high-level programming languages
C To accelerate network connections
D To synchronize processes or threads and coordinate resource access

Explanation: A semaphore is a synchronization primitive used to coordinate concurrent execution and control access to shared resources through operations that change or wait on its count.

Question 12: Which scheduling algorithm can cause starvation when shorter jobs continually arrive?

A Shortest Job First
B Round Robin with a fixed time quantum
C First-Come, First-Served
D A strictly fair cyclic scheduler

Explanation: Non-preemptive Shortest Job First scheduling may indefinitely delay a long job if shorter jobs repeatedly arrive and are selected ahead of it.

Question 13: What is thrashing in a virtual memory system?

A The permanent deletion of virtual memory
B The process of increasing the CPU's clock speed
C Excessive paging that leaves little time for useful execution
D The conversion of physical memory into cache memory

Explanation: Thrashing occurs when excessive page faults cause the system to spend most of its time transferring pages between RAM and secondary storage rather than executing useful work.

Question 14: Which page replacement algorithm replaces the page that has not been used for the longest time in the past?

A First-In, First-Out
B Least Recently Used
C First-Come, First-Served
D Round Robin

Explanation: Least Recently Used (LRU) replaces the page whose most recent access occurred furthest in the past. It uses past access history to approximate which page is least likely to be needed soon.

Question 15: What is the purpose of a system call?

A To physically connect a monitor to the computer
B To replace the computer's BIOS permanently
C To increase the number of CPU cores
D To request operating system services from a user-space program

Explanation: A system call provides a controlled interface through which a user-space program requests services from the operating system kernel, such as file access or process creation.

Question 16: Which of the following is one of the four necessary conditions for deadlock?

A Guaranteed resource preemption
B Unlimited parallel execution
C Circular wait
D Automatic process completion

Explanation: Circular wait occurs when processes form a cycle in which each process waits for a resource held by the next process. Together with mutual exclusion, hold and wait, and no preemption, it forms the four Coffman conditions for deadlock.

Question 17: In a Unix-like operating system, what does the fork() system call typically do?

A Creates a new process
B Formats the entire hard drive
C Deletes the operating system kernel
D Changes the processor's physical architecture

Explanation: The fork() system call creates a new process by duplicating the calling process. The child receives a separate process identity, and memory is commonly managed using copy-on-write.

Question 18: What is a race condition?

A A process running faster than the CPU clock
B A hardware component overheating during startup
C A file being copied between two directories
D A program's result depending on the timing or ordering of concurrent operations

Explanation: A race condition occurs when the result of a computation depends on the timing or ordering of concurrent operations accessing shared state, and the operations are not adequately coordinated.

Question 19: What is the primary difference between preemptive and non-preemptive CPU scheduling?

A Preemptive scheduling works only on computers without memory
B Preemptive scheduling allows the operating system to interrupt a running process
C Non-preemptive scheduling always requires multiple processors
D There is no difference between the two approaches

Explanation: In preemptive scheduling, the operating system can interrupt a running process and allocate the CPU to another process. In non-preemptive scheduling, a running process retains the CPU until it terminates or voluntarily yields or blocks.

Question 20: What is the main purpose of a Translation Lookaside Buffer (TLB)?

A To store copies of all user documents
B To schedule processes according to their priority
C To speed up virtual-to-physical address translation
D To manage network routing tables exclusively

Explanation: A TLB is a small, fast cache that stores recently used virtual-to-physical address translations. A TLB hit avoids the need to perform a full page-table lookup for that translation.

Question 21: What is a process in the context of operating systems?

A A program in execution
B A static file stored on the hard drive
C A hardware component like the CPU
D A device driver for a printer

Explanation: A process is a program in execution, representing an active unit of work.

Question 22: Which data structure is typically used to represent a process's control information in the OS?

A Queue
B Process Control Block (PCB)
C Stack pointer table
D Inverted index

Explanation: The Process Control Block (PCB) contains all the information needed about a specific process.

Question 23: Which of the following scheduling algorithms is non-preemptive?

A Round Robin
B First-Come, First-Served (FCFS)
C Shortest Remaining Time First
D Priority Preemptive

Explanation: First-Come, First-Served (FCFS) is strictly non-preemptive as once the CPU has been allocated to a process, it keeps the CPU until it releases it.

Question 24: What is Belady's anomaly associated with?

A CPU scheduling algorithms
B Disk head scheduling algorithms
C Page replacement algorithms like FIFO
D Deadlock avoidance algorithms

Explanation: Belady's anomaly describes the phenomenon where increasing the number of page frames results in an increase in the number of page faults for certain memory access patterns under FIFO.

Question 25: What is a semaphore primarily used for?

A Memory allocation
B Process synchronization
C File system backup
D Network packet routing

Explanation: A semaphore is a synchronization tool used to manage concurrent processes and solve critical section problems.

Question 26: Which conditions must hold simultaneously for a deadlock to occur?

A Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait
B Preemption, Starvation, Aging, Spooling
C Context Switching, Paging, Segmentation, Thrashing
D Interrupts, Dispatching, Multiprogramming, Pooling

Explanation: Coffman conditions for deadlock are Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait.

Question 27: What does Thrashing mean in an operating system?

A The CPU is running at maximum frequency
B Processes spend more time paging than executing instructions
C The hard disk drive has experienced a mechanical failure
D Network connections are dropping packets continuously

Explanation: Thrashing occurs when a system spends more time paging (swapping pages in and out of memory) than executing actual instructions.

Question 28: Which of the following system calls creates a new process in UNIX-like operating systems?

A exec()
B fork()
C spawn()
D clone()

Explanation: The fork() system call creates a new child process that is a duplicate of the calling process.

Question 29: What is the primary objective of a time-sharing operating system?

A To minimize response time
B To maximize hardware cost efficiency
C To run batch jobs overnight without interaction
D To eliminate the need for secondary storage

Explanation: Time-sharing systems switch the CPU among processes so frequently that users can interact with each program while it is running, minimizing response time.

Question 30: What is a thread?

A A heavyweight process with its own address space
B A lightweight process within a process
C A type of physical memory chip
D An input-output hardware control bus

Explanation: A thread is a lightweight process, representing the basic unit of CPU utilization.

Question 31: Which page replacement algorithm replaces the page that has not been used for the longest period of time?

A FIFO
B Least Recently Used (LRU)
C Optimal Page Replacement
D Random Replacement

Explanation: Least Recently Used (LRU) uses past knowledge to replace the page that hasn't been referenced for the longest time.

Question 32: What is the main function of the kernel?

A To provide graphic web browsing capabilities
B To manage system resources and act as the core of the OS
C To translate high-level code into bytecode
D To handle user account passwords exclusively

Explanation: The kernel is the core component of the operating system that manages system resources and hardware communication.

Question 33: Which memory management technique eliminates external fragmentation?

A Contiguous memory allocation
B Segmentation
C Paging
D Variable partition allocation

Explanation: Paging divides physical memory into fixed-size blocks called frames and logical memory into blocks called pages, completely eliminating external fragmentation.

Question 34: What is a page fault?

A A syntax error detected by the compiler
B An interruption when a requested page is not in physical memory
C A hardware failure in the RAM stick
D A security violation caused by unauthorized access

Explanation: A page fault occurs when a program attempts to access a memory page that is not currently mapped in physical RAM.

Question 35: What is the Banker's algorithm used for?

A Deadlock avoidance
B Process scheduling
C Disk defragmentation
D Memory compression

Explanation: The Banker's algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety conditions.

Question 36: Which component provides the interface between user applications and the operating system services?

A System calls
B Compilers
C Linkers
D Loaders

Explanation: System calls provide the interface between a running program and the operating system.

Question 37: Which disk scheduling algorithm moves the disk arm to the end of the disk servicing requests in one direction before reversing?

A FCFS
B SCAN
C SSTF
D C-LOOK

Explanation: The SCAN disk scheduling algorithm (elevator algorithm) moves continuously toward one end, servicing requests until it reaches the end, then reverses direction.

Question 38: What is context switching?

A Changing the user interface theme
B Saving the state of a current process and loading the state of another
C Switching a computer from sleep mode to active mode
D Moving data between primary memory and secondary storage

Explanation: Context switching involves storing the context or state of a current process so that it can be restored later, and loading the state of another process.

Question 39: What is virtual memory?

A An illusion of a large memory maintained by using disk space as an extension of RAM
B A cloud storage system managed by the browser
C Cache memory integrated directly inside the CPU die
D Read-only memory storing the bootloader

Explanation: Virtual memory is a memory management capability that uses hardware and software to allow a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.

Question 40: Which file allocation method uses a linked list of disk blocks for each file?

A Contiguous allocation
B Linked allocation
C Indexed allocation
D Direct allocation

Explanation: Linked allocation links each file as a linked list of disk blocks, where each block contains a pointer to the next block.

Question 41: Which of the following is an example of a batch operating system?

A IBM OS/360
B Windows 10
C macOS Sonoma
D Android 14

Explanation: Batch systems execute jobs with similar needs in batches without user interaction during execution, common in early mainframe systems.

Question 42: What does RAID stand for in storage management?

A Redundant Array of Independent Disks
B Random Access Information Directory
C Rapid Access Internal Device
D Remote Application Interface Data

Explanation: RAID stands for Redundant Array of Independent Disks, used to improve performance and reliability.

Question 43: What is spooling?

A Compressing large files to save disk space
B Placing data in temporary storage for a peripheral device to access later
C Spreading process threads across multiple CPU sockets
D Encrypting network streams against interception

Explanation: SPOOLing (Simultaneous Peripheral Operations On-Line) is a process where data is held in temporary storage to be used by a device later, commonly used for printing.

Question 44: Which scheduling metric measures the total time spent from submission of a process to its completion?

A Waiting time
B Turnaround time
C Response time
D Throughput

Explanation: Turnaround time is the total time taken to execute a process from its arrival time to its completion time.

Question 45: What is a microkernel architecture?

A An architecture where all OS services run inside kernel space
B An architecture that structures the OS by removing non-essential components from the kernel
C An operating system designed exclusively for microcontrollers
D A kernel that fits entirely within the L1 CPU cache

Explanation: A microkernel structures the operating system by removing all non-essential components from the kernel and implementing them as system programs in user space.

Question 46: What is the purpose of the program counter (PC) register in a process state?

A To store the total memory size allocated to the process
B To hold the address of the next instruction to be executed
C To count the number of system calls made
D To record the total CPU ticks consumed

Explanation: The program counter holds the address of the next instruction to be executed for that process.

Question 47: Which of the following is NOT a valid process state?

A Ready
B Running
C Compile
D Terminated

Explanation: Standard process states include New, Ready, Running, Waiting (Blocked), and Terminated. 'Compile' is not a process state.

Question 48: What is internal fragmentation?

A Unused space left inside an allocated memory block
B Free memory scattered in small blocks between allocated partitions
C Data corruption inside the CPU cache registers
D Disorganized files on a fragmented hard disk drive

Explanation: Internal fragmentation occurs when allocated memory blocks are larger than the requested memory, leaving unused space inside the partition.

Question 49: What is external fragmentation?

A Unused memory space within a single allocated partition
B Sufficient total free memory exists, but it is not contiguous
C Hard drive sectors damaged by magnetic wear
D Network data packets lost during transmission

Explanation: External fragmentation happens when total free memory is enough to satisfy a request, but it is not contiguous.

Question 50: Which scheduling algorithm can suffer from the convoy effect?

A Round Robin
B First-Come, First-Served (FCFS)
C Shortest Job First
D Multilevel Feedback Queue

Explanation: The convoy effect occurs in FCFS when shorter processes wait behind a long CPU-bound process.

Quiz: Operating Systems

Operating Systems

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