An operating system acts as an intermediary between user applications and the computer hardware. It manages resources and provides essential services for programs.

Operating systems handle tasks like memory management, process scheduling, and file management. Spreadsheet processing is an application-level function, not a core OS responsibility.

Kernel mode provides full access to hardware resources and allows sensitive instructions to be executed. User mode restricts such operations to prevent unintended interference with the system.

A process is essentially a program in execution. It includes the current activity, allocated resources, and other operating system related information necessary for its execution.

First-Come, First-Served (FCFS) is a basic scheduling algorithm that processes tasks sequentially as they arrive. The other options are algorithms used for sorting or searching, not for scheduling processes.

The Process Control Block (PCB) is essential for managing processes as it stores key information like process state, register data, and resource allocation. This data is crucial during context switches and scheduling decisions.

Round Robin scheduling allocates a fixed time slice to each process, ensuring that all processes receive fair CPU time. This is especially effective in time-sharing systems where responsiveness is essential.

Deadlock is a condition where processes become stuck waiting for one another to release resources. This circular waiting prevents any involved process from proceeding.

The classical conditions for deadlock are mutual exclusion, hold and wait, no preemption, and circular wait. 'Resource Utilization' does not form part of these conditions.

Paging is the mechanism where fixed-size blocks of memory, called pages, are moved between physical memory and disk storage. This facilitates the implementation of virtual memory and efficient memory management.

System calls provide a controlled interface for user applications to request services from the kernel. This mechanism upholds system security and stability by regulating access to hardware resources.

Paging splits both physical and logical memory into equal, fixed-size blocks known as pages. This uniform division facilitates easier memory allocation and swapping between memory and disk.

Thrashing occurs when the OS spends too much time swapping pages between memory and disk, leaving little time for actual process execution. This results in significantly degraded system performance.

Multiprogramming allows multiple programs to reside in memory simultaneously, with the CPU switching between them to maximize utilization. This concurrent processing increases overall system efficiency.

A page table maps virtual addresses used by a program to physical addresses in memory. This translation is fundamental to the concept of virtual memory and allows systems to use more memory than physically available.

By eliminating one of the necessary conditions for deadlock (such as hold and wait), the system can prevent deadlock scenarios. Prevention techniques proactively modify resource allocation strategies to avoid circular dependencies.

The time quantum defines how long a process can run before a context switch occurs in Round Robin scheduling. An optimally chosen time quantum helps achieve a balance between responsiveness and the overhead of frequent context switches.

A hierarchical file system organizes files into directories and subdirectories, which makes it easier for users to locate and manage their files. This structure improves overall file management and navigation compared to a flat file system.

Context switching involves saving the current state of a running process and restoring the state of a new process. This mechanism is crucial for enabling multitasking in an operating system.

Interrupt latency is the time gap from when an interrupt is signaled to when the processor begins to respond. Minimizing this delay is critical for ensuring the system can handle real-time events effectively.