Basic components of a computer system

A closed system-unit case acts as a protective enclosure for internal parts. Leaving it open exposes fans, circuit boards, and connectors to dust, accidental contact, spills, and foreign objects. Therefore, option A is correct. An open case does not update software, increase RAM capacity, or guarantee faster networking; those outcomes depend on software, hardware, and network conditions.

The governing concept is the input-process-output cycle. Input devices enter data, the processor performs operations, and output devices communicate the finished result through a screen, printer, speaker or similar unit. Since the question states that input and processing are successful, the failure is in presenting or transmitting the result to the user. That identifies the output unit, making option A correct; the other choices occur earlier or serve different purposes.

The governing concept is volatility. Random-access memory, or RAM, needs continuous electrical power to retain the programs and data currently being used. When power is switched off, its contents are generally lost, which is why RAM is called volatile or temporary memory. ROM, flash memory, and optical discs are non-volatile storage and normally retain data without power. Therefore, option C is correct.

The motherboard is the computer’s main printed circuit board and acts as the connection platform for the processor, memory, storage interfaces, expansion cards, and other internal parts. Its buses, sockets, and connectors allow these components to exchange data and receive control signals. Therefore, option A is correct. A printer, sound recorder, or internet transfer function belongs to a peripheral or network device, not to the motherboard alone.

The Power Supply Unit, or PSU, receives electricity from the wall outlet and converts it into regulated voltage levels required by the motherboard, processor, drives, and other components. It also distributes power through suitable connectors. Therefore, option C is correct. A scanner, monitor, and mouse may use power, but none supplies and regulates power for the whole computer’s internal hardware.

A heat sink is a thermally conductive metal component placed on or attached to the processor. It absorbs heat from the processor and spreads it through fins, increasing surface area so air can carry the heat away. Option D is therefore correct. A cooling fan moves air but is not the metal heat-spreading block, while sound cards, network cards, and memory modules perform different functions.

A cooling fan moves air across heat sinks and other warm components, helping maintain a safe operating temperature. If it stops, heat is removed less effectively, so the processor and nearby internal parts may overheat. Option A is correct. Overheating can cause slow performance, instability, automatic shutdown, or hardware damage; it cannot increase storage, mouse speed, or monitor memory.

A traditional hard disk drive stores data magnetically on one or more rotating platters coated with magnetic material. A read/write head changes or detects magnetic patterns while the platters spin. Therefore, option C is correct. Flash cells are used by SSDs, paper strips are not standard HDD media, and main memory is temporary working storage rather than the disk’s storage medium.

The Graphics Processing Unit, or GPU, is designed to perform many calculations for displaying and manipulating images, animations, and video. It processes visual data in parallel and sends rendered output toward the display system, making option D correct. A PSU supplies electricity, a sound card handles audio, and a network card handles communication data; none is mainly designed for graphics computation.

A Network Interface Card, or NIC, provides the hardware interface through which a computer communicates over a wired network. Its network port and circuitry send and receive data using a cable and the appropriate networking standards. Option A is correct. A sound card processes audio, a graphics card processes visual output, and cache memory temporarily holds frequently needed data; none primarily provides wired network connectivity.

A sound card, also called an audio adapter, handles audio input from devices such as microphones and audio output sent to speakers or headphones. It converts and processes signals so the computer can record, play, and manage sound. Option B is correct. A graphics card handles visuals, a storage controller manages drives, and the motherboard battery preserves firmware settings or the clock rather than processing audio.

The CMOS battery supplies a small, continuous amount of power to the real-time clock and CMOS settings on the motherboard when the computer is switched off. This is why the system can remember the date, time, and some basic hardware settings. Main memory loses its contents without power, while a fan and speaker do not store clock information. Therefore, option C is correct.

A computer bus is a group of electrical pathways used for communication between internal components such as the processor, memory, and input-output controllers. Different buses may carry data, memory addresses, or control signals, but the general name for this shared internal communication pathway is bus. A pixel is an image element, a folder organizes files, and a port is a connection interface. Thus, option D is correct.

A touchscreen combines two functions in one physical device. Its display panel produces visual output by showing text, images, and controls, while its touch-sensitive layer detects a finger or stylus and sends that action to the computer as input. The other options describe neither both functions nor the normal role of a touchscreen: playing sound, printing, or storing data. Thus, option D is correct.

A scanner uses an optical sensing system to read text or an image from paper and convert it into digital information, commonly saved as an image or document file. It is therefore an input device because information enters the computer through it. A monitor displays output, a printer produces paper output, and a webcam captures live scenes rather than being the usual device for digitizing a flat paper document. Option A is correct.

A printer converts digital text, images, or other computer results into a physical hard copy on paper. This output is called permanent because it remains available on the printed sheet even after the computer is turned off. A microphone, mouse, and webcam are input devices: they send sound, movement, or images into the computer. They do not normally create paper output. Therefore, option B is correct.

A projector receives visual signals from a computer and enlarges the corresponding text, images, or video onto a wall or large screen. It is therefore a visual output device, useful in classrooms and presentations. A keyboard sends typed input, a scanner sends paper information into the computer, and a modem handles communication over a network. None of those devices is primarily used to display a large projected image. Option C is correct.

A microphone detects sound waves and converts them into an electrical signal that the computer can process, record, or transmit as digital audio. It is therefore an audio input device. Headphones and speakers generally convert electrical or digital signals into sound for listening, so they are output devices, while a monitor displays visual information. The device that enters a person’s voice into the computer is the microphone. Hence, option D is correct.

The governing concept is that different input devices perform different jobs. Pointer movement indicates that the mouse is responding, but entering letters requires the keyboard. Therefore, the keyboard and its connection should be checked first. The monitor only displays output, the speaker produces sound, and the projector displays an enlarged image; none of these normally accepts typed characters. Hence option A is correct.

The governing concept is the separation of output functions. A monitor can display visual information even when the audio pathway has a fault. Sound is produced through speakers, with the sound card or audio circuitry processing and sending the signal. Thus the speakers, sound card, volume setting, or audio connection should be checked. A scanner captures images, a mouse controls the pointer, and a hard disk stores data, so option B is correct.

The governing concept is the distinction between the computer’s enclosure and its external peripherals. The system unit, often called the computer case or cabinet, houses the motherboard, processor, main memory, power supply, and other internal parts. A monitor displays information, a printer creates paper output, and a peripheral is a broader category for connected devices. The processor is only one component inside the enclosure, not its name. Therefore option D is correct.

The governing concept is the classification of hardware according to its relationship with the computer. A printer or scanner is an external device connected to provide input or output, so it is called a peripheral device. A kernel is core operating-system software, a register is a tiny high-speed storage location inside the processor, and firmware is embedded control software. These alternatives are not categories for the external device itself. Therefore option A is correct.

The governing concept is the versatility of a standard computer port. USB ports can connect many kinds of peripherals, including keyboards, mice, printers, storage drives, cameras, and other compatible devices; they may also transfer data and sometimes supply power. USB is not restricted to monitors, does not replace RAM, and has no primary role in cooling the processor. Thus the broad connectivity described in option B is the major advantage.

The governing concept is the purpose of multimedia connectors. HDMI, meaning High-Definition Multimedia Interface, is designed to carry digital video and digital audio through one compatible cable, which reduces the need for separate display and sound connections. An audio jack normally carries sound only, a mouse connector is for a pointing device, and an older USB type is not identified primarily as a combined video-audio display link. Therefore option C is correct.

The governing concept is the role of RAM in active program execution. Random Access Memory temporarily holds the operating system, open applications, and data currently being used by the processor. Increasing RAM gives more working space and can improve multitasking, provided the system supports the upgrade. A monitor displays information, while a printer and scanner handle output and input; none provides temporary program memory. Therefore option A is correct.