Olete.in – MCQs, Mock Tests & Government Job Prep | Operating system Operating Systems MCQs

Supervisor call :-

1. is a call made by the supervisor of the system
2. is a call with a control functions
3. are pixilated calls that are used to perform resource management functions
4. in a call made by someone working in root directory

✅ Correct Answer: 3

Round-robin scheduling is essentially the preemptive version of :-

1. FIFO
2. Shortest job first
3. shortest remaining time first
4. longest time first

✅ Correct Answer: 4

FIFO scheduling is :-

1. Preemptive scheduling
2. Non preemptive scheduling
3. deadline scheduling
4. fare share scheduling

✅ Correct Answer: 2

In real time operating system,which of the following is the most suitable scheduling algorithms

1. Round-robin
2. FCFS
3. preemptive
4. Random

✅ Correct Answer: 3

In round-robin CPU scheduling, as the time quantum is increased , the average turn around time

1. increase
2. decrease
3. remain constant
4. varies irreguraly

✅ Correct Answer: 4

Preemptive scheduling is the strategy of temporarily suspending a running process

1. before the CPU time slice expires
2. to allow starving process to run
3. when it request I/O
4. None of the above

✅ Correct Answer: 1

Which of the following statements is true? 1. Shortest remaining time first scheduling may cause starvation 2.Preemptive scheduling may cause starvation 3. Round robin is better than FCFS in terms

1. 1 only
2. 1 and 3
3. 2 and 3
4. 1,2 and 3

✅ Correct Answer: 4

Function of operating system :-

1. resource utilization
2. resource allocation
3. file management
4. All of the above

✅ Correct Answer: 4

In which state, a process goes to the CPU

1. New
2. Running
3. Waiting
4. Ready

✅ Correct Answer: 2

If a process require a input/output then process goes to

1. ready state
2. running state
3. waiting state
4. none of the above

✅ Correct Answer: 3

Which of the following statements are true?

1. value of binary semaphore is a subset of value of counting semaphore
2. counting semaphore is a subset of binary semaphore
3. binary semaphore contain only 0 or 1
4. 1 and 3 are true

✅ Correct Answer: 4

At particular time, the value of a counting semaphore is 10. It will become 7 after

1. 3V operation
2. 3P operation
3. 13 P operation and 10 V operation
4. 2 and 3

✅ Correct Answer: 4

At particular time, the value of a counting semaphore is 4. It will become 7 after

1. 3V operation
2. 3P operation
3. 13 P operation and 10 V operation
4. All of the above

✅ Correct Answer: 1

At particular time, the value of a counting semaphore is 10. It will become 9 after

1. 1P operation
2. 1V operation
3. 2P operation and 3V operation
4. 1 and 3

✅ Correct Answer: 1

At particular time of computation the value of a counting semaphore in 7. Then 20P operation and X V operation were performed on this semaphore. If the final value of semaphore is 5, X will be -

1. 22
2. 18
3. 15
4. 13

✅ Correct Answer: 2

Value of Counting semaphore is -

1. 0 or 1
2. 7
3. Natural number
4. All of the above

✅ Correct Answer: 4

A critical region

1. is a piece of code which only one process execute at a time
2. is a region prone to deadlock
3. is a piece of code which only a finite number of process execute
4. None of the above

✅ Correct Answer: 1

A thread -

1. is a light weight process where the context switching is low
2. is a light weight process where the context switching is high
3. is used to speed up paging
4. None of the above

✅ Correct Answer: 2

which one is a high level abstraction over semaphore ?

1. shared memory
2. message passing
3. monitor
4. mutual exclusion

✅ Correct Answer: 3

A binary semaphore

1. has the value one or zero
2. is essential to binary computers
3. is used only for synchronization
4. is used only for mutual exclusion

✅ Correct Answer: 1

A threads is a

1. Heavy weight process
2. multi process
3. inter-tread process
4. light weight process

✅ Correct Answer: 4

Consider The following statements with respect to user clever threads and kernel supported threads: a. context switch is faster with kernel supported threads b. for user level threads, a system call

1. a,c,d
2. b,c
3. a,c
4. a,b

✅ Correct Answer: 2

Necessary condition for deadlock

1. Mutual exclusion
2. Hold and wait
3. No preemption and circular wait
4. All of the above

✅ Correct Answer: 4

Method of handling deadlock ?

1. deadlock avoidance
2. deadlock prevention
3. deadlock detection and prevention
4. All of the above

✅ Correct Answer: 4

Banker algorithms is a example of

1. deadlock avoidance
2. deadlock prevention
3. deadlock detection and prevention
4. All of the above

✅ Correct Answer: 1

Mutual exclusion is a problem occurs between

1. two disjoint process that do not interact
2. processes that share resources
3. processes that do not use the some resources
4. None of the above

✅ Correct Answer: 2

A system has 3 processes sharing 4 resources. If a each process need maximum of 2 units, then

1. deadlock can never occur
2. deadlock may occur
3. deadlock has to occur
4. None of the above

✅ Correct Answer: 1

With a single resource, deadlock occurs

1. if there are more than one processes competing for that resources
2. if there are only two processes competing for that resources
3. if there is a single processes competing for that resources
4. None of the above

✅ Correct Answer: 1

Processes wait for infinite time in

1. Deadlock
2. starvation
3. Both of the above
4. None of the above

✅ Correct Answer: 3

A state is safe if the system call allocate resources to each process(upto its maximum) in same order and still avoid deadlock. Then

1. deadlock state is safe
2. unsafe state may lead deadlock situation
3. deadlock state is subset of unsafe state
4. All of the above

✅ Correct Answer: 1

Resources are allocated to a process on non-shareable basic in

1. Mutual exclusion
2. Hold and wait
3. No preemption
4. circular wait

✅ Correct Answer: 1

The method of dealing with deadlock problem is

1. use a protocol to make sure that the system never enters to a deadlock stat
2. allow a system to enter a deadlock state and increases
3. ignore the problem and pretend that deadlocks never occur
4. All of the above

✅ Correct Answer: 4

Which of the following is NOT a valid deadlock prevention scheme?

1. Release all resources before requesting a new resource
2. Number the resources uniquely and never request a lower numbered resource t
3. Never request a resource after releasing any resource
4. Request and all required resources be allocated before execution

✅ Correct Answer: 3

Consider a virtual memory system with FIFO page replacement policy. For an arbitrary page access pattern, increasing the number of page frames in main memory will

1. Always decrease the number of page faults
2. Always increase the number of page faults
3. Some times increase the number of page faults
4. Never affect the number of page faults

✅ Correct Answer: 3

Which of the following requires a device driver?

1. Disk
2. Cache
3. Main memory
4. Register

✅ Correct Answer: 1

Consider three CPU-intensive processes, which require 10, 20 and 30 time units and arrive at times 0, 2 and 6, respectively. How many context switches are needed if the operating system implements a s

1. 1
2. 2
3. 3
4. 4

✅ Correct Answer: 2

A CPU generates 32-bit virtual addresses. The page size is 4 KB. The processor has a translation look-aside buffer (TLB) which can hold a total of 128 page table entries and is 4-way set associative.

1. 11 bit
2. 20 bit
3. 13 bit
4. 15 bit

✅ Correct Answer: 4

In which one of the following page replacement policies, BeladyÃ¢â&sbquo;¬â&bdquo;¢s anomaly may occur?

1. FIFO
2. Optimal
3. LRU
4. MRU

✅ Correct Answer: 1

The essential content(s) in each entry of a page table is / are

1. Virtual page number
2. Page frame number
3. Both of the above
4. None of the above

✅ Correct Answer: 2

Consider a disk system with 100 cylinders. The requests to access the cylinders occur in following sequence: 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, wh

1. 190ms
2. 256ms
3. 119ms
4. 341ms

✅ Correct Answer: 3

A process executes the code fork(); fork(); fork(); The total number of child processes created is

1. 3
2. 4
3. 5
4. 7

✅ Correct Answer: 4

Total number of child processes created by following program is for(i=0;i<3;i++) fork();

1. 3
2. 0
3. 7
4. 6

✅ Correct Answer: 3

Total number of child processes created by following program is for(i=0;i<4;i++) fork();

1. 15
2. 4
3. 7
4. 1

✅ Correct Answer: 1

Total number of child processes created by following program is for(i=0;i<1;i++) fork();

1. 7
2. 2
3. 0
4. 1

✅ Correct Answer: 4

Total number of child processes created by following program is x for(i=0;i<8;i++) fork(); then x-250= ?

1. 5
2. 0
3. 6
4. 1

✅ Correct Answer: 3

A file system with 300 GByte uses a file descriptor with 8 direct block address. 1 indirect block address and 1 doubly indirect block address. The size of each disk block is 128 Bytes and the size of

1. 3KB
2. 34KB
3. 35KB
4. 21KB

✅ Correct Answer: 3

A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because

1. It reduces the memory access time to read or write a memory location
2. It helps to reduce the size of page table needed to implement the virtual a
3. It is required by the translation lookaside buffer
4. It helps to reduce the number of page faults in page replacement algorithm

✅ Correct Answer: 2

Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table?

1. 2 MB
2. 12 MB
3. 16 MB
4. 8 MB

✅ Correct Answer: 1

A system uses FIFO policy for page replacement. It has 4 page frames with no pages loaded to begin with. The system first accesses 100 distinct pages in some order and then accesses the same 100 pages

1. 196
2. 197
3. 123
4. 234

✅ Correct Answer: 1

Memory protection is of no use in

1. single user system
2. non-multiprogramming system
3. non-multitasking system
4. None of the above

✅ Correct Answer: 4

In which of the following page replacement policies Belady anomaly may occur ?

1. FIFO
2. Optimal
3. LRU
4. MRO

✅ Correct Answer: 1

A page fault occurs

1. when page is not in the memory
2. when the page is in the memory
3. when the page is in blocked state
4. when process is in new state

✅ Correct Answer: 1

Virtual memory is commonly implemented by -

1. segmentation
2. fragmentation
3. demand paging
4. page replacement

✅ Correct Answer: 1

The mechanism that bring a page into memory only when it is needed is called-

1. segmentation
2. fragmentation
3. demand paging
4. page replacement

✅ Correct Answer: 3

Which of the following statement is false?

1. segmentation suffers from external fragmentation
2. paging suffer from internal fragmentation
3. segmented memory can be paged
4. virtual memory is used only in multi user system

✅ Correct Answer: 4

The first fit best fit and worst fit algorithm can be used for-

1. contiguous memory allocation
2. linked allocation of memory
3. index allocation of memory
4. All of the above

✅ Correct Answer: 1

The essential contents in each entry of a page table is -

1. Virtual page number
2. Page frame number
3. both virtual and page frame
4. access right information

✅ Correct Answer: 1

A file is

1. an abstraction data type
2. logical storage unit
3. file is usually non volatile
4. All of the above

✅ Correct Answer: 4

The simplest directly structure is -

1. single level directory
2. two level directory
3. tree structure directory
4. None of the above

✅ Correct Answer: 1

Disadvantage of single level directory is -

1. the confusion of file names between different user
2. the confusion of file data
3. Both of the above
4. None of the above

✅ Correct Answer: 1

Solution of name collision problem is

1. single level directory
2. two level directory
3. tree structure directory
4. None of the above

✅ Correct Answer: 2

which structure prohibits sharing of file and directory

1. single level directory
2. two level directory
3. tree structure directory
4. None of the above

✅ Correct Answer: 3

There are no cycle in which of the directory -

1. general graph directory
2. a cyclic graph directory
3. one level directory
4. two level directory

✅ Correct Answer: 2

The lowest level of I/O control consists of -

1. device drivers
2. interrupt handles
3. Both of the above
4. None of the above

✅ Correct Answer: 3

Access time is the highest in case of

1. floopy disk
2. cache
3. swapping device
4. magnetic disk

✅ Correct Answer: 4

What is the shell ?

1. It is hardware component
2. It is command interpreter
3. It is a part in compiler
4. It is a tool in CPU scheduling

✅ Correct Answer: 2

If the disk head located initially at 32, find the no of disk moves required with FCFS if the disk queue of I/O block requests are 98,37,14,124,65,67

1. 310
2. 324
3. 315
4. 343

✅ Correct Answer: 4

Magnetic tape can serve as

1. input media
2. output media
3. Secondary storage media
4. All of the above

✅ Correct Answer: 4

Supervisor state is

1. entered by program when they enter the processor
2. required to perform any I/O
3. only allowed to the operating system
4. never used

✅ Correct Answer: 3

The operating systems manages

1. memory
2. processor
3. disk and I/O devices
4. All of the above

✅ Correct Answer: 2

PCB is stands for -

1. program control block
2. process control block
3. process communication block
4. None of the above

✅ Correct Answer: 2

Which of the following file name extension suggests that the file is backup copy of another file ?

1. TXT
2. COM
3. BAS
4. BAK

✅ Correct Answer: 4

Which is not the state of the process ?

1. Blocked
2. Ready
3. Running
4. privileged

✅ Correct Answer: 4

Which is the state of process ?

1. Blocked
2. Ready
3. Running
4. All of the above

✅ Correct Answer: 4

The problem of thrashing is effected by scientifically by-

1. program structure
2. program size
3. primary storage size
4. None of the above

✅ Correct Answer: 1

The number of processes completed per unit time is known as

1. output
2. throughput
3. efficiency
4. capacity

✅ Correct Answer: 2

What is the memory from 1k to 640k called ?

1. Extended memory
2. normal memory
3. low memory
4. conventional memory

✅ Correct Answer: 4

Process state is a part of

1. process control block
2. inode
3. file allocation table
4. None of the above

✅ Correct Answer: 2

A program at time of execution is called ?

1. dynamic program
2. static program
3. binded program
4. a process

✅ Correct Answer: 1

A thread is a ?

1. Heavy weight process
2. multi process
3. inter-thread process
4. light weight process

✅ Correct Answer: 4

The state of process after it encounters an I/O instruction is

1. ready
2. blocked / waiting
3. idle
4. running

✅ Correct Answer: 2

The major problem with priority scheduling is ?

1. definite blocking
2. starvation
3. low priority
4. None of the above

✅ Correct Answer: 2

______ OS pays more attention on the meeting of the the time limit

1. distributed
2. network
3. real time
4. online

✅ Correct Answer: 1

A process said to be in ______ state if it was waiting for an event that will never occur

1. safe
2. unsafe
3. starvation
4. deadlock

✅ Correct Answer: 3

The operating system of a computer serve as a software between the user and the

1. hardware
2. peripheral
3. memory
4. screen

✅ Correct Answer: 1

The removal of process from active contention of CPU and reintroduce them into memory later is known as

1. interrupt
2. swapping
3. signal
4. thread

✅ Correct Answer: 3

_______ allocates the largest hole available in the memory

1. Best fit
2. Worst fit
3. First fit
4. None of the above

✅ Correct Answer: 2

A binary semaphore -

1. has the value one or zero
2. is essential to binary computers
3. is used only for synchronization
4. is used only for mutual exclusion

✅ Correct Answer: 1

The hardware mechanism that enable a device to notify the CPU is called

1. polling
2. interrupt
3. system call
4. None of the above

✅ Correct Answer: 3

The banker algorithms is used

1. to prevent deadlock in operating systems
2. to detect deadlock in operating systems
3. to rectify a deadlock state
4. None of the above

✅ Correct Answer: 1

Which data structure are used for process scheduling ?

1. stack
2. tree
3. queue
4. heap

✅ Correct Answer: 3

_______ is a high level abstraction over semaphore

1. shared memory
2. message passing
3. monitor
4. mutual exclusion

✅ Correct Answer: 3

How many page faults occur for optimal page replacement following reference string, with four page frames ? 1,2,3,4,5,3,4,1,6,7,8,7,8,9,7,8,9,5,4,5,4,2

1. 14
2. 13
3. 11
4. 12

✅ Correct Answer: 3

If you dont know which version of MS-DOS you are working with, which command will you use after booting your operating system ?

1. format command
2. FAT command
3. VER command
4. DISK command

✅ Correct Answer: 4

How many page faults occur in LRU replacement following reference string, with four page frames ? 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1

1. 8
2. 7
3. 6
4. 9

✅ Correct Answer: 2

Which scheduling policy is most suitable for a time sharing operating systems ?

1. Shortest job first
2. Round robin
3. First come first serve
4. Elevator

✅ Correct Answer: 2

A processor needs software interrupts to

1. test the interrupt system of the processor
2. implement coroutine
3. obtain system services which need execution of privileged instruction
4. return from subroutine

✅ Correct Answer: 3

Which of the following does not interrupt a running process

1. A device
2. timer
3. scheduler process
4. power failure

✅ Correct Answer: 1

System calla are usually invoked by using

1. a software interrupt
2. polling
3. an indirect jump
4. a privileged instruction

✅ Correct Answer: 1