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

Operating Systems MCQ Questions