Q1. A process is:

A) A program in execution
B) A file stored in memory
C) An input device
D) A compiler

Answer: A

Explanation: A process is a program that is currently being executed by the CPU.

Q2. PCB stands for:

A) Program Control Block
B) Process Control Block
C) Processor Control Block
D) Process Command Block

Answer: B

Explanation: PCB stores information about a process such as process state, PID, registers, etc.

Q3. Which of the following is not a process state?

A) Ready
B) Running
C) Waiting
D) Compiling

Answer: D

Explanation: Compiling is not a process state. Common states are Ready, Running, Waiting, etc.

Q4. Context switching occurs when:

A) CPU changes from one process to another
B) File is deleted
C) Memory is formatted
D) Printer starts printing

Answer: A

Explanation: Context switching happens when CPU saves one process state and loads another.

Q5. Which scheduler selects processes from the ready queue?

A) Long-term scheduler
B) Short-term scheduler
C) Medium-term scheduler
D) Disk scheduler

Answer: B

Explanation: Short-term scheduler selects processes from the ready queue for CPU execution.

Q6. Long-term scheduler is also called:

A) CPU scheduler
B) Job scheduler
C) Device scheduler
D) Memory scheduler

Answer: B

Explanation: Long-term scheduler is called Job scheduler because it selects jobs from secondary memory.

Q7. Which scheduling algorithm is simplest?

A) FCFS
B) SJF
C) Round Robin
D) Priority Scheduling

Answer: A

Explanation: First Come First Serve (FCFS) is the simplest scheduling algorithm.

Q8. FCFS stands for:

A) First Control First Serve
B) First Come First Serve
C) Fast Come Fast Serve
D) First CPU First Serve

Answer: B

Explanation: FCFS executes processes in the order they arrive.

Q9. SJF stands for:

A) Shortest Job First
B) Smallest Job First
C) Short Job Format
D) System Job First

Answer: A

Explanation: SJF selects the process with the shortest burst time first.

Q10. Round Robin scheduling mainly uses:

A) Priority
B) Time Quantum
C) Semaphore
D) Deadlock

Answer: B

Explanation: Round Robin uses a fixed time quantum for each process.

Q11. Which scheduling algorithm may cause starvation?

A) FCFS
B) SJF
C) Round Robin
D) FIFO

Answer: B

Explanation: In SJF, longer processes may wait indefinitely, causing starvation.

Q12. Time Quantum is used in:

A) FCFS
B) SJF
C) Round Robin
D) Deadlock Detection

Answer: C

Explanation: Time Quantum is the fixed CPU time assigned in Round Robin scheduling.

Q13. Turnaround Time means:

A) Completion Time – Arrival Time
B) Burst Time – Waiting Time
C) Exit Time – Ready Time
D) Start Time – Arrival Time

Answer: A

Explanation: Turnaround Time is the total time taken from arrival to completion.

Q14. Waiting Time means:

A) CPU time used
B) Time spent in ready queue
C) Completion time
D) Response time

Answer: B

Explanation: Waiting Time is the total time a process spends waiting in the ready queue.

Q15. Response Time means:

A) First response to process request
B) Completion of process
C) File opening time
D) Memory allocation time

Answer: A

Explanation: Response Time is the time from submission until the first response is produced.

Q16. Thread is:

A) Lightweight process
B) Heavyweight process
C) Deadlock state
D) Memory block

Answer: A

Explanation: A thread is called a lightweight process because it uses fewer resources.

Q17. Multithreading means:

A) Multiple CPUs
B) Multiple threads in one process
C) Multiple files
D) Multiple users

Answer: B

Explanation: Multithreading allows multiple threads to execute within a single process.

Q18. Which is faster?

A) Process switching
B) Thread switching
C) File switching
D) Disk switching

Answer: B

Explanation: Thread switching is faster because threads share the same memory space.

Q19. Preemptive scheduling means:

A) Process can be interrupted
B) Process runs forever
C) No CPU allocation
D) Only one process exists

Answer: A

Explanation: In preemptive scheduling, a running process can be interrupted by the OS.

Q20. Non-preemptive scheduling means:

A) Process cannot be interrupted
B) CPU is idle
C) No scheduling happens
D) No process execution

Answer: A

Explanation: In non-preemptive scheduling, a process keeps CPU until it finishes or blocks.

Q21. CPU utilization means:

A) Percentage of CPU busy time
B) RAM usage
C) Hard disk usage
D) Number of files

Answer: A

Explanation: CPU utilization measures how much time CPU remains busy.

Q22. Throughput means:

A) Number of completed processes per unit time
B) Memory speed
C) CPU speed
D) File transfer speed

Answer: A

Explanation: Throughput tells how many processes are completed in a given time.

Q23. Which algorithm is best for time-sharing systems?

A) FCFS
B) Round Robin
C) SJF
D) Priority

Answer: B

Explanation: Round Robin is best for time-sharing because each process gets equal CPU time.

Q24. Which scheduling algorithm gives minimum average waiting time?

A) FCFS
B) SJF
C) RR
D) FIFO

Answer: B

Explanation: SJF usually provides the minimum average waiting time.

Q25. RM stands for:

A) Rate Monotonic
B) Round Memory
C) Real Machine
D) Random Method

Answer: A

Explanation: RM is a real-time scheduling algorithm called Rate Monotonic Scheduling.

Q26. EDF stands for:

A) Earliest Deadline First
B) Easy Data First
C) Early Data Function
D) End Deadline Function

Answer: A

Explanation: EDF is a real-time scheduling algorithm where the nearest deadline gets priority.

Q27. Multiprocessor scheduling is used when:

A) One CPU exists
B) Multiple CPUs exist
C) No CPU exists
D) Only memory exists

Answer: B

Explanation: Multiprocessor scheduling is used when the system has more than one CPU.

Q28. Process ID is stored in:

A) ROM
B) PCB
C) CPU
D) Cache

Answer: B

Explanation: Process ID (PID) is stored inside the Process Control Block.

Q29. Which scheduler controls the degree of multiprogramming?

A) Short-term scheduler
B) Long-term scheduler
C) Medium-term scheduler
D) CPU scheduler

Answer: B

Explanation: Long-term scheduler controls how many processes enter the system.

Q30. Thread shares:

A) Separate memory
B) Same address space
C) Different CPU
D) Separate disk

Answer: B

Explanation: Threads of the same process share the same memory and resources.