GATE CS 2024 Set 1 — Question 25

MSQ+1 / -0EasyProcess States & PCBProcesses & ThreadsOperating System

Operating System → Processes & Threads → Process States & PCB

Last updated 20 August 2026

Question

Which of the following process state transitions is/are NOT possible?

Correct answer (B) Waiting to Running; (C) Ready to Waiting Solution In a standard five-state process transition model (New, Ready, Running, Waiting, Terminated): 1. Running to Ready : This is a possible transition. It occurs when a process is preempted (e.g., its time quantum expires in a Round Robin scheduling algorithm). 2. Waiting to Running : This is NOT possible . A process in the Waiting (or Blocked) state must first transition to the Ready state once the event it was waiting for (like I/O completion) occurs. From the Ready state, the CPU scheduler can then dispatch it to the Running state. 3. Ready to Waiting : This is NOT possible . A process can only enter the Waiting state from the Running state. This happens when the process makes a system call for an I/O operation or needs to wait for a specific event to occur. 4. Running to Terminated : This is a possible transition. It occurs when a process finishes its execution or is terminated due to an error. Therefore, the transitions that are not possible are (B) and (C). Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (B) Waiting to Running; (C) Ready to Waiting Solution In a standard five-state process transition model (New, Ready, Running, Waiting, Terminated): 1. Running to Ready : This is a possible transition. It occurs when a process is preempted (e.g., its time quantum expires in a Round Robin scheduling algorithm). 2. Waiting to Running : This is NOT possible . A process in the Waiting (or Blocked) state must first transition to the Ready state once the event it was waiting for (like I/O completion) occurs. From the Ready state, the CPU scheduler can then dispatch it to the Running state. 3. Ready to Waiting : This is NOT possible . A process can only enter the Waiting state from the Running state. This happens when the process makes a system call for an I/O operation or needs to wait for a specific event to occur. 4. Running to Terminated : This is a possible transition. It occurs when a process finishes its execution or is terminated due to an error. Therefore, the transitions that are not possible are (B) and (C).

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