Operating Systems MCQs

Question 1

What is the main difference between a process and a thread?

Accepted Answer

A process has its own memory space, while threads within the same process share memory

Answer

A thread always runs faster than a process

Answer

A process can only run one instruction at a time

Answer

Threads cannot communicate with each other

Question 2

Which CPU scheduling algorithm can lead to starvation of longer processes?

Accepted Answer

Priority scheduling without aging

Answer

Shortest Job First (SJF)

Answer

First Come First Served (FCFS)

Answer

Round Robin

Question 3

What is a race condition?

Accepted Answer

A situation where the outcome of a program depends on the unpredictable timing of concurrent operations accessing shared data

Answer

A condition where a program runs faster than expected

Answer

An error that occurs only during compilation

Answer

A scheduling algorithm used in real time systems

Question 4

What is the purpose of a semaphore in operating systems?

Accepted Answer

To control access to a shared resource by multiple processes or threads using a counter

Answer

To measure the CPU usage of a process

Answer

To store the memory address of the next instruction

Answer

To schedule processes based on arrival time

Question 5

What is virtual memory?

Accepted Answer

A memory management technique that gives processes the illusion of a large, continuous address space by using disk storage as an extension of RAM

Answer

A type of memory that only exists temporarily during compilation

Answer

A backup copy of RAM stored on a separate physical machine

Answer

Memory that is shared exclusively between the CPU and GPU

Question 6

What is thrashing in the context of operating systems?

Accepted Answer

A state where the system spends more time swapping pages in and out of memory than executing actual processes

Answer

A technique used to speed up disk access

Answer

A method for detecting deadlocks

Answer

The process of formatting a hard disk

Question 7

What is the purpose of the Banker's Algorithm?

Accepted Answer

To avoid deadlock by only granting resource requests that leave the system in a safe state

Answer

To schedule processes based on their memory size

Answer

To allocate CPU time fairly among threads

Answer

To manage disk defragmentation automatically

Question 8

What distinguishes preemptive scheduling from non-preemptive scheduling?

Accepted Answer

Preemptive scheduling can interrupt a running process to give the CPU to another process, while non-preemptive scheduling cannot

Answer

Non-preemptive scheduling always runs faster than preemptive scheduling

Answer

Preemptive scheduling only applies to single core systems

Answer

Non-preemptive scheduling is used exclusively in real time operating systems

Question 9

What is a page fault?

Accepted Answer

An event that occurs when a program accesses a page that is not currently loaded in physical memory

Answer

A hardware failure in the CPU

Answer

An error caused by writing to a read-only file

Answer

A type of deadlock involving multiple threads

Question 10

What is the primary purpose of a context switch?

Accepted Answer

To save the state of a currently running process and load the state of another process so the CPU can switch between them

Answer

To restart the operating system after a crash

Answer

To move a process from RAM to disk permanently

Answer

To convert a process into a thread

Question 11

What is the difference between a mutex and a semaphore?

Accepted Answer

A mutex allows only one thread to access a resource at a time, while a semaphore can allow a fixed number of threads based on its count

Answer

A mutex can allow multiple threads, while a semaphore only allows one

Answer

A semaphore is used only for file access, while a mutex is used only for memory access

Answer

There is no functional difference between the two

Question 12

What is the role of the kernel in an operating system?

Accepted Answer

It is the core component that manages hardware resources and provides essential services to other parts of the system

Answer

It is a user application used for writing documents

Answer

It is a type of file system used only on servers

Answer

It is a scheduling algorithm used for disk access

Question 13

Which disk scheduling algorithm selects the request closest to the current head position?

Accepted Answer

Shortest Seek Time First (SSTF)

Answer

First Come First Served (FCFS)

Answer

Round Robin

Answer

Priority Scheduling

Question 14

What is the purpose of an interrupt in operating systems?

Accepted Answer

To signal the CPU that an event requiring immediate attention has occurred, pausing the current task temporarily

Answer

To permanently stop a process from running

Answer

To increase the priority of a background process

Answer

To allocate additional memory to a running process

Question 15

What is the difference between internal and external fragmentation?

Accepted Answer

Internal fragmentation wastes space within an allocated block, while external fragmentation wastes space between allocated blocks

Answer

Both refer to the exact same problem with different names

Answer

Internal fragmentation only occurs in virtual memory systems

Answer

External fragmentation only occurs with fixed sized partitions

Question 16

What is the main advantage of multithreading within a single process?

Accepted Answer

Threads can share memory and resources, making communication between them faster than between separate processes

Answer

Threads always run on separate CPU cores automatically

Answer

Threads never need synchronization since they share memory

Answer

Multithreading eliminates the need for an operating system scheduler

Question 17

What is the function of a device driver in an operating system?

Accepted Answer

It acts as a translator between the operating system and a specific piece of hardware

Answer

It manages the file system's directory structure

Answer

It schedules which process runs next on the CPU

Answer

It compiles source code into machine instructions

Question 18

What does it mean for an operating system to be 'multitasking'?

Accepted Answer

It can execute multiple processes concurrently by rapidly switching the CPU between them

Answer

It can only run one program at a time but very quickly

Answer

It requires multiple physical CPUs to function

Answer

It automatically installs updates in the background

Question 19

What is the primary difference between paging and segmentation as memory management techniques?

Accepted Answer

Paging divides memory into fixed size blocks, while segmentation divides memory into variable sized logical units

Answer

Paging is used only for disk storage, while segmentation is used only for RAM

Answer

Segmentation always eliminates fragmentation entirely

Answer

Paging requires manual configuration by the programmer

Question 20

What happens during a system call?

Accepted Answer

A user program requests a service from the operating system kernel, such as reading a file

Answer

The operating system restarts a crashed application automatically

Answer

A process is permanently terminated by the scheduler

Answer

The CPU switches from kernel mode to a lower privilege level

Question 21

What is the purpose of a process control block (PCB) in an operating system?

Accepted Answer

It stores all the information needed to manage a process, such as its state, program counter, and register values

Answer

It stores the source code of a program

Answer

It permanently deletes a process once it starts

Answer

It only tracks how much disk space a process uses

Question 22

What is the difference between a long term scheduler and a short term scheduler?

Accepted Answer

The long term scheduler decides which jobs enter the system, while the short term scheduler decides which ready process runs next on the CPU

Answer

The long term scheduler runs every few milliseconds while the short term scheduler runs once a day

Answer

They are two names for the exact same component

Answer

The short term scheduler manages memory while the long term scheduler manages the disk

Question 23

What is a zombie process?

Accepted Answer

A process that has finished execution but still has an entry in the process table because its exit status has not been read by its parent

Answer

A process that runs forever without ever finishing

Answer

A process that has crashed the entire operating system

Answer

A process that uses no CPU time at all

Question 24

What does the term 'starvation' mean in the context of process scheduling?

Accepted Answer

A situation where a process waits indefinitely because higher priority processes keep getting selected first

Answer

A situation where the CPU runs out of power

Answer

A situation where a process uses too much memory

Answer

A situation where two processes finish at exactly the same time

Question 25

What is the purpose of the Least Recently Used (LRU) page replacement algorithm?

Accepted Answer

It replaces the page that has not been used for the longest period of time when a new page needs to be loaded

Answer

It replaces pages in the exact order they were loaded, regardless of usage

Answer

It replaces a page chosen completely at random

Answer

It never replaces any page once it is loaded

Question 26

What is the main purpose of spooling in an operating system?

Accepted Answer

It allows a slower device, such as a printer, to be used by multiple processes by temporarily storing data on disk until the device is ready

Answer

It compresses files before saving them

Answer

It speeds up the CPU clock rate

Answer

It prevents any two processes from ever running at the same time

Question 27

What is the difference between a hard real time system and a soft real time system?

Accepted Answer

A hard real time system must meet its deadlines without exception, while a soft real time system tolerates occasional missed deadlines

Answer

A hard real time system runs only on powerful servers, while a soft real time system runs only on small devices

Answer

There is no meaningful difference between the two terms

Answer

A soft real time system never has any deadlines at all

Question 28

What is the purpose of a swap space on disk?

Accepted Answer

It temporarily holds pages or processes moved out of main memory when RAM is full

Answer

It stores permanent copies of installed software

Answer

It is used exclusively for storing the operating system kernel

Answer

It speeds up network communication

Question 29

What is the belady's anomaly in page replacement algorithms?

Accepted Answer

A situation where increasing the number of page frames results in more page faults instead of fewer

Answer

A situation where a system runs out of disk space unexpectedly

Answer

A rule that says every algorithm must use exactly four page frames

Answer

A situation where the CPU stops responding to interrupts

Question 30

What is the purpose of an operating system's shell?

Accepted Answer

It provides an interface, either command line or graphical, that lets users interact with the operating system

Answer

It manages the physical memory chips directly

Answer

It is another name for the kernel itself

Answer

It only exists in older operating systems and is no longer used

Question 31

What is the main difference between a monolithic kernel and a microkernel?

Accepted Answer

A monolithic kernel runs most operating system services in a single large kernel space, while a microkernel keeps the kernel minimal and runs services in user space

Answer

A monolithic kernel can only run on a single CPU core

Answer

A microkernel does not support any device drivers at all

Answer

There is no real difference in how they are structured

Question 32

What is the purpose of the fork() system call in Unix-like operating systems?

Accepted Answer

It creates a new child process that is a copy of the calling parent process

Answer

It terminates the currently running process

Answer

It merges two processes into one

Answer

It changes the priority of a process

Question 33

What is the difference between paging and swapping?

Accepted Answer

Paging moves individual fixed-size blocks of memory, while swapping moves an entire process in or out of memory

Answer

Paging and swapping are two names for the exact same operation

Answer

Swapping only applies to CPU registers

Answer

Paging is used only in operating systems that do not support multitasking

Question 34

What is the purpose of the Round Robin CPU scheduling algorithm?

Accepted Answer

It gives each process a fixed time slice to run before moving to the next process in a cyclic order

Answer

It always runs the shortest job first regardless of arrival time

Answer

It runs processes strictly in the order they were created and never interrupts them

Answer

It only works with a single process at a time

Question 35

What is a critical section in operating systems?

Accepted Answer

A part of a program where shared resources are accessed and only one process or thread should execute at a time

Answer

A section of code that always runs first when a program starts

Answer

A part of memory reserved exclusively for the operating system kernel

Answer

A section of disk that cannot be read or written

Question 36

What is the purpose of the exec() system call in Unix-like systems?

Accepted Answer

It replaces the current process's memory image with a new program

Answer

It creates a brand new empty process with no code

Answer

It permanently pauses a process

Answer

It only works on background processes

Question 37

What is the purpose of a bootloader in the startup process of a computer?

Accepted Answer

It loads the operating system kernel into memory and hands over control to it

Answer

It manages user login screens after the operating system starts

Answer

It compiles application software before it runs

Answer

It only manages network connections

Question 38

What is the purpose of the Shortest Job First (SJF) scheduling algorithm?

Accepted Answer

It selects the process with the smallest estimated execution time to run next

Answer

It selects processes purely based on which one arrived first

Answer

It always runs the largest process available

Answer

It ignores execution time completely and runs processes randomly

Question 39

What is a livelock, and how does it differ from a deadlock?

Accepted Answer

In a livelock, processes keep changing state in response to each other without making real progress, while in a deadlock processes are completely stuck and unable to change state at all

Answer

A livelock and a deadlock describe exactly the same situation

Answer

A livelock only happens on single core processors

Answer

A livelock is fixed automatically by the operating system without any special handling

Question 40

What is the purpose of memory protection in an operating system?

Accepted Answer

It prevents one process from accessing or modifying the memory belonging to another process

Answer

It compresses memory to save space

Answer

It permanently locks all memory so nothing can ever be changed

Answer

It only applies to read only memory chips

Question 41

What is the purpose of a file allocation table (FAT) in a file system?

Accepted Answer

It keeps track of which disk blocks belong to each file and where the next block of that file is located

Answer

It is used only to store user passwords

Answer

It stores the actual content of every file

Answer

It manages network file sharing exclusively

Question 42

What is the difference between a user level thread and a kernel level thread?

Accepted Answer

A user level thread is managed by a library in user space without kernel awareness, while a kernel level thread is managed and scheduled directly by the operating system

Answer

A kernel level thread can only exist inside device drivers

Answer

A user level thread always runs faster than any kernel operation

Answer

There is no real difference between the two

Question 43

What is the purpose of the operating system's I/O scheduler for disk requests?

Accepted Answer

It decides the order in which pending disk read and write requests are serviced to improve efficiency

Answer

It decides which programs are allowed to be installed

Answer

It manages only network requests, not disk requests

Answer

It prevents any disk access from ever happening at the same time

Question 44

What is meant by 'demand paging' in virtual memory management?

Accepted Answer

Pages are loaded into memory only when they are actually referenced by a running process, rather than all at once

Answer

All pages of a process are loaded into memory before it starts running

Answer

Pages are loaded in a fixed order determined at compile time

Answer

Demand paging refers to loading an entire program from a network location

Question 45

What is the purpose of the operating system's 'nice' value for a process in Unix-like systems?

Accepted Answer

It adjusts the scheduling priority of a process, with higher values generally giving it lower priority

Answer

It permanently sets a fixed amount of memory for a process

Answer

It renames the process to something more readable

Answer

It disables the process from ever being terminated

Question 46

Which condition is NOT one of Coffman’s four necessary conditions for deadlock to occur?

Accepted Answer

Preemption enabled

Answer

Mutual exclusion

Answer

Hold and wait

Answer

Circular wait

Question 47

Which of the following is NOT one of Coffman’s four necessary conditions for deadlock to occur?

Accepted Answer

Preemption Allowed

Answer

Mutual Exclusion

Answer

Circular Wait

Answer

Hold and Wait

Operating Systems Practice Test

Operating Systems MCQ Questions