16) The state of a process after it encounters an I/O instruction is __________
1 Ready
2 Blocked/Waiting
3 Idle
4 Running
Right Ans ) 2

17) The number of processes completed per unit time is known as __________
1 Output
2 Throughput
3 Efficiency
4 Capacity
Right Ans ) 2

18) _________ is the situation in which a process is waiting on another process,which is also waiting on another process  which is waiting on the first process None of the processes involved in this circular wait are making progress
1 Deadlock
2 Starvation
3 Dormant
4 None of the above
Right Ans ) 1

19) Which of the following file name extension suggests that the file is Backup copy of another file ?
Right Ans ) 4

20) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy?
1 Time-sharing
2 SPOOLing
3 Preemptive scheduling
4 Multiprogramming
Right Ans ) 4

21) A critical region
1 is a piece of code which only one process executes at a time
2 is a region prone to deadlock
3 is a piece of code which only a finite number of processes execute
4 is found only in Windows NT operation system
Right Ans ) 1

22) 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
Right Ans ) 3

23) PCB =
1 Program Control Block
2 Process Control Block
3 Process Communication Block
4 None of the above
Right Ans ) 2

24) FIFO scheduling is ________
1 Preemptive Scheduling
2 Non Preemptive Scheduling
3 Deadline Scheduling
4 Fair share scheduling
Right Ans ) 2

25) Switching the CPU to another Process requires to save state of the old process and loading new process state is called as __________
1 Process Blocking
2 Context Switch
3 Time Sharing
4 None of the above
Right Ans ) 2

26) Which directory implementation is used in most Operating System?
1 Single level directory structure
2 Two level directory structure
3 Tree directory structure
4 Acyclic directory structure
Right Ans ) 3

27) The Banker¿s algorithm is used
1 to prevent deadlock in operating systems
2 to detect deadlock in operating systems
3 to rectify a deadlocked state
4 none of the above
Right Ans ) 1

28) A thread
1 is a lightweight process where the context switching is low
2 is a lightweight process where the context swithching is high
3 is used to speed up paging
4 none of the above
Right Ans ) 1

29) ______ is a high level abstraction over Semaphore
1 Shared memory
2 Message passing
3 Monitor
4 Mutual exclusion
Right Ans ) 3

30) A tree sturctured file directory system
1 allows easy storage and retrieval of file names
2 is a much debated unecessary feature
3 is not essential when we have millions of files
4 none of the above
Right Ans ) 1




1)Virtual memory is ?

  1. Extremely large main memory
  2. Extremely large secondary memory
  3. An illusion of an extremely large memory
  4. Atype of memory used in super computers


Answer = C 
  Virtual memory is a feature of Operating System that enables a process to use a memory independent of other processes



2) Spatial locality refers to the problem that once a location  is referenced  ?

  1. It will not be referenced again
  2. It will be referenced again
  3. A nearby location will be referenced soon
  4. None of Above


Answer =  B
 Spatial locality or locality of reference stats that the same value or related value is going to be referenced again



3)  Which of the following is an example of SPOOLED device?

  1. The terminal used to enter the input data for a program being executed
  2. The secondary memory device in a virtual memory system
  3. A line printer used to print the output of number of job’s
  4. None of above


Answer = C 
Line printer used to print the output of number of job’s is an example of print spooling In print spooling documents are loaded into the buffer and then the printer pulls then off the buffer at its own rate

4) Page fault occurs when ?

  1. The page in corrupted byapplication software
  2. The page is in main memory
  3. The page is not in main memory
  4. One tries to divide number by 0


Answer = C
Page fault occurs when the page that is not in the main memory is tried to be accessed

5)  Overlays is ?

  1. A part of Operating System
  2. A specific memory location
  3. A single contiguous memory that was used in the olden days for running large programs by swapping
  4. Overloading the system with many user files


Answer = C
  An overlay is when a process replaces itself with the code of another program
6) Determine the number of page faults when references to pages occurs in the order 1,2,4,5,2,1,2,4 Assume that the main memory can accommodate 3 pages and the main memory already has the pages 1 and 2 With page 1 having been brought earlier that page 2(Assume LRU algorithm is used) ?

  1. 3
  2. 5
  3. 4
  4. None


Answer = C 
As the reference string is 1,2,4,5,2,1,2,4 so if LRU page replacement algorithm is used then there will be 4 page faults

7) Concurrent processed are processed that ?

  1. Do not overlap in time
  2. Overlap in time
  3. Are executed by processor at thesame time
  4. None of Above


Answer = B 
Concurrent means something that executed at the same time ad something else

8) The rage replacement policy that sometimes leads to more page faults when the size of the memory is increased is ?

  1. FIFO
  2. LRU
  3. no such policy exists
  4. None of Above


Answer = A 
If the size of memory is increased and FIFO page replacement algorithm is used then there will be more page faults

9) The only transition that is initiated by the user process itself is ?

  1. block
  2. dispatch
  3. wake up
  4. None of Above


10) Working set(r,k) at an instance of time t, is a set of ?

  1. k future references that operating system will make
  2. Future references that the operating system will make in the next ‘k’ time units
  3. k references with high frequency
  4. Pages that have been referenced in the last k time units


Answer = D