Basic components of a computer system

Correct answer: C. Hard disk

Explanation: A hard disk, including a modern hard disk drive or similar internal storage drive, keeps files and software for long-term use. Therefore, option C is correct. It is non-volatile secondary storage, so data normally remains after shutdown. A mouse is an input and pointing device, a monitor displays information, and a microphone captures sound; none of these is intended for permanent file storage.

Correct answer: D. Pen drive

Explanation: A pen drive is a small USB flash-storage device designed to save files and carry them conveniently between compatible computers. Thus, option D is correct. It is a portable, non-volatile storage medium. A speaker produces sound, a monitor presents visual output, and a printer makes paper copies; these devices may use data but are not intended to transport and store files.

Correct answer: A. Motherboard

Explanation: The motherboard is the main printed circuit board that provides physical connections and communication pathways for important internal parts such as the processor, memory, storage interfaces, and expansion components. Therefore, option A is correct. The taskbar is a software interface element, a mouse pad supports a mouse, and a keypad supplies user input; none connects the internal hardware.

Correct answer: B. Power supply unit

Explanation: The power supply unit, or PSU, converts incoming electrical power into the regulated voltages and currents required by the computer’s internal components. Therefore, option B is correct. A graphics card processes visual output, a sound card handles audio signals, and a network card manages network communication. These components may consume power, but they do not distribute the computer’s main electrical supply.

Correct answer: C. Graphics card

Explanation: The governing concept is specialized computer hardware: a graphics card processes visual data and sends image or video signals to the monitor. Therefore, option C is correct. A network card manages network communication, a sound card handles audio signals, and a memory card stores data. The words image, video, and display point directly to graphics hardware.

Correct answer: D. Sound card

Explanation: The governing concept is the role of expansion cards in processing different types of signals. A sound card processes audio input and output, allowing a computer to receive signals from a microphone and send them to speakers or headphones. Thus, option D is correct. A graphics card handles images and video, a network card handles communication, and a memory card stores data.

Correct answer: A. Network Interface Card (NIC)

Explanation: The governing concept is network connectivity hardware. A Network Interface Card, or NIC, provides the interface through which a computer joins a wired or wireless network and exchanges data. Therefore, option A is correct. A sound card processes audio, a graphics card processes visual output, and a memory card stores information rather than providing network access.

Correct answer: B. Modem

Explanation: The governing concept is signal conversion in internet communication. A modem, whose name comes from modulator-demodulator, converts signals from an Internet Service Provider into data that a computer or local network can use, so option B is correct. A router forwards or distributes data between networks, while a scanner and speaker perform input and audio output functions.

Correct answer: C. Monitor

Explanation: The governing concept is the distinction between input and output devices. A monitor is an output device that presents processed information as text, images, or video on a screen, so option C is correct. A keyboard enters typed data, a scanner converts paper material into digital input, and a microphone captures sound; none of these displays the final result.

Correct answer: D. Router

Explanation: The governing concept is routing, which means selecting a path for packets of data. A router examines network information and forwards data between separate networks, such as a home network and the internet. Therefore, option D is correct. A keyboard, webcam, and scanner are input devices that provide data to a computer; they do not direct traffic between networks.

Correct answer: A. Cooling fan

Explanation: The governing concept is computer thermal management. A cooling fan actively moves air through the system and helps carry heat away from components such as the CPU, so option A is correct. A heat sink also transfers and spreads heat, but it is a passive metal component; the question asks for the cooling component that circulates air. A mouse and printer do not cool internal hardware.

Correct answer: B. Heat sink

Explanation: The governing concept is heat dissipation in computer hardware. A heat sink is a metal component, usually made with fins, that draws heat away from the CPU and spreads it over a larger surface so air can carry it away. Hence, option B is correct. Sound and network cards provide other functions, while a pen drive is external storage and does not cool the processor.

Correct answer: C. System unit

Explanation: The governing concept is the physical organization of computer hardware. The system unit, commonly housed in a computer cabinet or case, contains major internal parts such as the motherboard, processor, memory, storage devices, and power supply. Therefore, option C is correct. A taskbar and desktop are interface elements, while a mouse pad is only a surface for using a mouse.

Correct answer: D. Optical disc drive

Explanation: The governing concept is removable optical storage. An optical disc drive uses a laser to read data from discs such as CDs and DVDs and, when it supports recording, to write data on writable discs. Thus, option D is correct. A scanner digitizes paper material, a speaker produces audio, and a modem converts communication signals; none of them reads or writes optical discs.

Correct answer: A. Solid-state drive (SSD)

Explanation: The governing concept is secondary storage: it preserves files even when the computer is switched off. A solid-state drive, or SSD, stores data in flash memory and usually provides faster access than a traditional hard disk because it has no moving parts. A microphone and webcam input data, while a speaker produces sound, so none of those provides permanent file storage. Therefore, option A is correct.

Correct answer: B. Cache memory

Explanation: The governing concept is the memory hierarchy. Cache memory is a small, high-speed memory located in or very near the CPU. It keeps frequently or recently needed instructions and data so the processor can access them more quickly than it can access RAM or secondary storage. A hard disk, pen drive, and DVD are storage devices that are farther from the CPU and generally slower. Therefore, option B is correct.

Correct answer: D. Hard disk

Explanation: Secondary storage retains data and programs for long-term use, normally even after power is removed. A hard disk is a secondary-storage device because it records files on magnetic media and allows them to be retrieved later. A mouse and keyboard send input to the computer, while a monitor displays output; neither is used to preserve files. Thus, option D is the only suitable answer.

Correct answer: A. Input devices

Explanation: The governing concept is the input-process-output cycle. Input devices transfer data or commands from a user or environment into the computer for processing. A keyboard, mouse, scanner, and microphone are common examples. Output devices show or produce results, storage devices retain data, and cooling devices control temperature. Since the question asks about entering data, option A, Input devices, is correct.

Correct answer: B. Output devices

Explanation: The governing concept is the output stage of a computer system. Output devices present processed data in a form that people can see, hear, or otherwise use. A monitor displays text and images, a printer produces paper copies, and speakers produce sound. Input devices enter data, processing devices perform operations, and network devices support communication. Therefore, the devices that provide results are output devices, making option B correct.

Correct answer: C. Processor

Explanation: The governing concept is processing. The processor, or central processing unit (CPU), interprets instructions, performs arithmetic and logical operations, and transforms input data into useful results. A printer and speaker are output devices, while a scanner is an input device that captures information. These devices may participate in the overall system, but they do not execute the instructions. Hence, option C is correct.

Correct answer: D. Storage device

Explanation: The governing concept is data storage and persistence. Storage devices save files, programs, and other data so that they can be retrieved later, often even after the computer is turned off. Hard disks, solid-state drives, memory cards, and pen drives are examples. A mouse and microphone provide input, while a speaker gives audio output. Therefore, option D correctly identifies the component that keeps files for future use.

Correct answer: B. Data

Explanation: The governing concept is the distinction between data and information. Raw facts, figures, symbols, or observations that have not yet been organised or interpreted are called data. When a computer processes and arranges data so that it has meaning for a purpose, the result is information. Software consists of instructions, and hardware means physical equipment. Thus, the phrase “raw facts” makes option B, Data, correct.

Correct answer: C. Information

Explanation: The governing concept is information processing. Data begins as raw facts, such as numbers or observations. After a computer organises, calculates, summarises, or interprets those facts in a useful context, the meaningful result is called information. Hardware is the physical equipment, instructions are commands that guide processing, and a cable connects devices. Therefore, processed and meaningful data is information, so option C is correct.

Correct answer: D. Software

Explanation: The governing concept is that software is the set of programs and instructions that tells hardware what to do and provides an interface for the user. Therefore, software helps a person operate hardware and complete tasks. Paper, a chair, and a table are physical objects, not computer-control components, so option D is correct.

Correct answer: A. System software

Explanation: The governing concept is software classification. An operating system is system software because it manages memory, files, devices, and processor use while providing essential services to applications. It is not an input or output device, and it is not a storage medium. Thus, option A correctly identifies its type and function.