UGC NET · PAPER 2
UGC NET Paper 2 Computer Science – Unit 5: System Software and Operating System PYQ (June 2025)
Q2. Once the process is allocated CPU and executing, which of the following events could NOT occur?
A. The process could issue an I/O request and then be placed in the Ready Queue
B. The process could create new subprocesses & wait for the termination of the subprocesses
C. The time slice of the process expires and it may join the waiting queue
D. The process is forcibly removed from the CPU and is put in the Waiting queue due to arrival of an interrupt
Choose the correct answer from the options given below:
A. The process could issue an I/O request and then be placed in the Ready Queue
B. The process could create new subprocesses & wait for the termination of the subprocesses
C. The time slice of the process expires and it may join the waiting queue
D. The process is forcibly removed from the CPU and is put in the Waiting queue due to arrival of an interrupt
Choose the correct answer from the options given below:
- B Only
- D Only
- A and C Only
- A, C and D Only
Q4. What shall be the average waiting time per process if we know that 10 processes (on average) arrive every second and there are normally 20 processes in the queue?
- 03 seconds
- 02 seconds
- 18 seconds
- 09 seconds
Q19. Which of the following shows the correct hierarchy of a layered file system in an operating system?
A. Logical File System
B. File Organization Module
C. Basic File System
D. I/O Control
E. Application Programs
Choose the correct answer from the options given below:
A. Logical File System
B. File Organization Module
C. Basic File System
D. I/O Control
E. Application Programs
Choose the correct answer from the options given below:
- A → B → D → C → E
- D → E → C → A → B
- E → A → B → C → D
- E → C → B → A → D
Q30. Consider the following interrupt protection levels in Linux, and arrange them in the increasing order of their priorities.
A. User-Mode Programs (Preemptible)
B. Bottom Half Interrupt Handlers
C. Top Half Interrupt Handlers
D. Kernel System Service Routines (Preemptible)
Choose the correct answer from the options given below:
A. User-Mode Programs (Preemptible)
B. Bottom Half Interrupt Handlers
C. Top Half Interrupt Handlers
D. Kernel System Service Routines (Preemptible)
Choose the correct answer from the options given below:
- B → A → C → D
- C → B → A → D
- C → A → B → D
- A → D → B → C
Q56. Match List I with List II
| List I | List II |
|---|---|
| A. Clustered Page Table | I. Generally considered inappropriate for 64 bit architectures. |
| B. Hierarchical Page Table | II. Has only one entry for each real page (or frame) of memory. |
| C. Segmentation | III. Useful for sparse address spaces. |
| D. Inverted Page Table | IV. Supports a user view of the system. |
- A → III, B → IV, C → II, D → I
- A → III, B → I, C → IV, D → II
- A → II, B → III, C → I, D → IV
- A → IV, B → III, C → II, D → I
Q58. Identify the correct statement(s) from the following with respect to Spinlock Semaphores
A. The name refers to busy waiting semaphores.
B. They are not useful when the locks are to be held for a short duration of time.
C. It may require multiple context switches when a process waits on a lock.
D. They are often employed on Uniprocessor systems.
Choose the correct answer from the options given below:
A. The name refers to busy waiting semaphores.
B. They are not useful when the locks are to be held for a short duration of time.
C. It may require multiple context switches when a process waits on a lock.
D. They are often employed on Uniprocessor systems.
Choose the correct answer from the options given below:
- A Only
- D Only
- B, D Only
- A, C and D Only
Q62. What is the total swap time (swap in + swap out) in a system for a 15 MB process with a transfer rate of 30 MBps? Given that there is an average latency of 12 ms, however no head seeks are involved.
- 1.024 sec
- 1.00 sec
- 0.512 sec
- 12 sec
Q64. Match List I with List II
| List I | List II |
|---|---|
| A. RAID Level 2 | I. Block interleaved distributed parity |
| B. RAID Level 3 | II. Also known as P+Q redundancy scheme |
| C. RAID Level 5 | III. Bit interleaved parity |
| D. RAID Level 6 | IV. Also known as memory style error correcting code organization |
- A → IV, B → III, C → I, D → II
- A → III, B → IV, C → I, D → II
- A → I, B → III, C → IV, D → II
- A → II, B → IV, C → I, D → III
Q67. Consider the following table about processes, their burst time and arrival time. Which process shall finish second last as per the respective Gantt charts for non-preemptive SJF and Round Robin (time quantum = 10) scheduling methods?
| Process | Burst Time | Arrival Time |
|---|---|---|
| P1 | 9 | 0 |
| P2 | 30 | 0 |
| P3 | 4 | 0 |
| P4 | 8 | 2 |
| P5 | 11 | 6 |
- SJF: P4; RR: P4
- SJF: P5; RR: P4
- SJF: P4; RR: P3
- SJF: P5; RR: P5
Q71. Which of the following statements is correct for Pthreads?
- It refers to POSIX standard (IEEE 1002.1c)
- This standard defines API for thread creation only
- This is a specification only for thread behavior and not its implementation
- Operating systems like Solaris, Linux, Mac OS X, except Tru64 UNIX, implement Pthreads
Directions (Q96–100): Consider the following disk queue with requests for I/O to blocks on cylinders:
45, 81, 185, 33, 175, 99, 150, 77
(Consider that the head starts from location 58.)
Q96. What shall be the 2nd request processed by the C-LOOK (Right) disk scheduling technique for the given request queue?
- 81
- 45
- 77
- 33
Q97. What shall be the total head movement of cylinders for the C-SCAN disk scheduling technique if the head starts moving in the right direction from the initial position? (Assume cylinders 0–199)
- 327
- 307
- 525
- 385
Q98. What shall be the 2nd request processed by the SCAN (Left) disk scheduling technique for the given request queue?
- 81
- 15
- 33
- 175
Q99. What will be the total head movement of cylinders for the SSTF disk scheduling technique?
- 160
- 124
- 177
- 240
Q100. What shall be the total head movement of cylinders if the FCFS disk scheduling method is used?
- 536
- 594
- 647
- 700