OS · Processes & Threads interview questions

48 real OS · Processes & Threads questions from the Computer Science Fundamentals bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is Process?

Junior
  1. A.a passive set of instructions stored on disk that becomes a process only when loaded and run
  2. B.an optimization where parent and child share pages after fork until one writes, then the page is copied
  3. C.a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  4. D.a program in execution with its own address space, code, data, stack and a PCB
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3. Which statement is correct?

Junior
  1. A.Process — a program in execution with its own address space, code, data, stack and a PCB
  2. B.Process — mechanisms like pipes, message queues and shared memory that let separate processes exchange data
  3. C.Process — a still-running child whose parent has terminated, so it gets adopted by the init process
  4. D.Process — a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
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4. What is Thread?

Junior
  1. A.the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
  2. B.a system call that creates a new child process as a near-duplicate copy of the calling parent
  3. C.the smallest unit of execution within a process that shares the process code, data and open files
  4. D.saving the state of one process and loading another so the CPU can switch between them
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6. Which statement is correct?

Junior
  1. A.Thread — an optimization where parent and child share pages after fork until one writes, then the page is copied
  2. B.Thread — mechanisms like pipes, message queues and shared memory that let separate processes exchange data
  3. C.Thread — the smallest unit of execution within a process that shares the process code, data and open files
  4. D.Thread — a passive set of instructions stored on disk that becomes a process only when loaded and run
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7. What is Program?

Junior
  1. A.a passive set of instructions stored on disk that becomes a process only when loaded and run
  2. B.a system call that creates a new child process as a near-duplicate copy of the calling parent
  3. C.the smallest unit of execution within a process that shares the process code, data and open files
  4. D.a kernel data structure storing a process's PID, state, registers, program counter and memory limits
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9. Which statement is correct?

Junior
  1. A.Program — the lifecycle of new, ready, running, waiting and terminated through which a process transitions
  2. B.Program — a still-running child whose parent has terminated, so it gets adopted by the init process
  3. C.Program — a passive set of instructions stored on disk that becomes a process only when loaded and run
  4. D.Program — a system call that creates a new child process as a near-duplicate copy of the calling parent
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10. What is Process Control Block?

Junior
  1. A.a kernel data structure storing a process's PID, state, registers, program counter and memory limits
  2. B.a system call that replaces a process's current memory image with a new program
  3. C.mechanisms like pipes, message queues and shared memory that let separate processes exchange data
  4. D.a terminated child whose exit status has not yet been collected by its parent via wait()
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11. Which term means: "a kernel data structure storing a process's PID, state, registers, program counter and memory limits"?

Junior
  1. A.Zombie process
  2. B.Context switch
  3. C.Process Control Block
  4. D.Context switch overhead
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12. Which statement is correct?

Junior
  1. A.Process Control Block — a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  2. B.Process Control Block — a kernel data structure storing a process's PID, state, registers, program counter and memory limits
  3. C.Process Control Block — an optimization where parent and child share pages after fork until one writes, then the page is copied
  4. D.Process Control Block — the lifecycle of new, ready, running, waiting and terminated through which a process transitions
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13. What is Process states?

Junior
  1. A.a system call that replaces a process's current memory image with a new program
  2. B.the lifecycle of new, ready, running, waiting and terminated through which a process transitions
  3. C.a program in execution with its own address space, code, data, stack and a PCB
  4. D.the smallest unit of execution within a process that shares the process code, data and open files
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15. Which statement is correct?

Junior
  1. A.Process states — the lifecycle of new, ready, running, waiting and terminated through which a process transitions
  2. B.Process states — saving the state of one process and loading another so the CPU can switch between them
  3. C.Process states — the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
  4. D.Process states — a terminated child whose exit status has not yet been collected by its parent via wait()
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16. What is Context switch?

Mid
  1. A.saving the state of one process and loading another so the CPU can switch between them
  2. B.a still-running child whose parent has terminated, so it gets adopted by the init process
  3. C.a passive set of instructions stored on disk that becomes a process only when loaded and run
  4. D.a system call that creates a new child process as a near-duplicate copy of the calling parent
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18. Which statement is correct?

Mid
  1. A.Context switch — the principle that switching threads of one process is cheaper because the address space need not change
  2. B.Context switch — a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  3. C.Context switch — saving the state of one process and loading another so the CPU can switch between them
  4. D.Context switch — an optimization where parent and child share pages after fork until one writes, then the page is copied
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19. What is Context switch overhead?

Mid
  1. A.the lifecycle of new, ready, running, waiting and terminated through which a process transitions
  2. B.a still-running child whose parent has terminated, so it gets adopted by the init process
  3. C.mechanisms like pipes, message queues and shared memory that let separate processes exchange data
  4. D.the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
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21. Which statement is correct?

Mid
  1. A.Context switch overhead — the lifecycle of new, ready, running, waiting and terminated through which a process transitions
  2. B.Context switch overhead — the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
  3. C.Context switch overhead — a kernel data structure storing a process's PID, state, registers, program counter and memory limits
  4. D.Context switch overhead — a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
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22. What is fork()?

Junior
  1. A.a kernel data structure storing a process's PID, state, registers, program counter and memory limits
  2. B.a system call that creates a new child process as a near-duplicate copy of the calling parent
  3. C.a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  4. D.the smallest unit of execution within a process that shares the process code, data and open files
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24. Which statement is correct?

Junior
  1. A.fork() — a system call that creates a new child process as a near-duplicate copy of the calling parent
  2. B.fork() — a system call that replaces a process's current memory image with a new program
  3. C.fork() — the smallest unit of execution within a process that shares the process code, data and open files
  4. D.fork() — a passive set of instructions stored on disk that becomes a process only when loaded and run
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25. What is exec()?

Junior
  1. A.a system call that replaces a process's current memory image with a new program
  2. B.an optimization where parent and child share pages after fork until one writes, then the page is copied
  3. C.a thread managed entirely by a user library that the kernel is unaware of, switching without kernel help
  4. D.the smallest unit of execution within a process that shares the process code, data and open files
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27. Which statement is correct?

Junior
  1. A.exec() — the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
  2. B.exec() — a system call that replaces a process's current memory image with a new program
  3. C.exec() — a thread managed entirely by a user library that the kernel is unaware of, switching without kernel help
  4. D.exec() — the lifecycle of new, ready, running, waiting and terminated through which a process transitions
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28. What is Zombie process?

Mid
  1. A.an optimization where parent and child share pages after fork until one writes, then the page is copied
  2. B.a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  3. C.saving the state of one process and loading another so the CPU can switch between them
  4. D.a terminated child whose exit status has not yet been collected by its parent via wait()
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30. Which statement is correct?

Mid
  1. A.Zombie process — the pure-overhead CPU time spent saving and restoring registers during a switch, doing no useful work
  2. B.Zombie process — a terminated child whose exit status has not yet been collected by its parent via wait()
  3. C.Zombie process — a thread the kernel creates and schedules directly, allowing true parallelism across multiple cores
  4. D.Zombie process — a thread managed entirely by a user library that the kernel is unaware of, switching without kernel help
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