Basic components of a computer system

Correct answer: C. Hard disk

Explanation: The governing concept is primary versus secondary storage. A hard disk is non-volatile storage, so it keeps files and software even after the computer is switched off. Therefore, option C is correct. RAM temporarily holds data while programs are running and loses its contents when power is removed. A keyboard is an input device, while a monitor is an output device, so neither is intended for long-term file storage.

Correct answer: D. Motherboard

Explanation: The governing concept is the role of a computer’s main circuit board. The motherboard provides connections and communication pathways for important parts such as the processor, memory, storage interfaces and expansion devices. Therefore, option D is correct. A mouse pad and printer tray are external accessories, while a screen panel displays information rather than connecting the internal components.

Correct answer: A. Arithmetic and Logic Unit

Explanation: The governing concept is the division of work inside the CPU. The Arithmetic and Logic Unit, or ALU, carries out numerical operations such as addition and subtraction and logical operations such as comparing two values. Therefore, option A is correct. The Control Unit coordinates instructions, the Storage Unit retains data, and the Input Unit receives commands from the user; none performs the ALU’s calculations.

Correct answer: B. Control Unit

Explanation: The governing concept is instruction control within the central processing unit. The Control Unit fetches and interprets instructions, then coordinates the movement of data and signals among the processor, memory and other components. Therefore, option B is correct. The Arithmetic Unit performs calculations, the Output Unit presents results, and the Storage Unit retains data; these units do not direct the entire sequence of operations.

Correct answer: C. Pen drive

Explanation: The governing concept is portable secondary storage. A pen drive uses flash memory and a USB connection to store and carry files between compatible computers. Therefore, option C is correct. A monitor displays visual output, a motherboard connects internal components, and a speaker produces sound. These devices may be moved, but they are not portable file-storage devices in the sense asked here.

Correct answer: D. USB port

Explanation: The governing concept is the function of computer ports. A pen drive normally has a USB connector, which fits into a computer’s USB port to transfer data and, when needed, receive power. Therefore, option D is correct. An audio jack is intended for sound equipment, a video port connects display devices, and a power button starts or shuts down the computer rather than transferring files.

Correct answer: A. Power Supply Unit

Explanation: The governing concept is power conversion and distribution inside a computer. The Power Supply Unit, or PSU, converts incoming electrical power into suitable voltages and distributes it to components such as the motherboard, drives and cooling devices. Therefore, option A is correct. RAM stores temporary working data, while a scanner and mouse are external input devices; none supplies power to the computer’s internal parts.

Correct answer: B. Cooling fan

Explanation: The governing concept is thermal management in computer hardware. A cooling fan moves air through or across the computer case, helping carry heat away from components such as the processor and power supply. Therefore, option B is correct. A printer produces paper output, while a keyboard and scanner provide input; none is designed to remove heat from internal parts. Proper airflow also supports reliable operation.

Correct answer: C. Input unit

Explanation: The governing concept is the input-process-output cycle. The input unit includes devices and mechanisms that accept commands or data from the user and send them into the computer for processing. Therefore, option C is correct. An output unit presents results, a storage unit retains data, and the Control Unit coordinates instructions after input has been received; none of these is the user-command entry group.

Correct answer: D. Output unit

Explanation: The governing concept is the output stage of the input-process-output cycle. After data is processed, the output unit communicates the results to the user through devices such as a monitor, printer or speaker. Therefore, option D is correct. The Input Unit accepts data, the Memory Unit stores information, and the Processing Unit performs operations; they do not primarily present the finished results to the user.

Correct answer: B. To display computer content on a large screen

Explanation: A projector is an output device that receives visual signals from a computer and enlarges them onto a screen or wall. Therefore, option B is correct because it is used to display computer content to a larger audience. A microphone records sound, a keyboard is used to type data, and a storage device keeps files; none of these functions describes a projector.

Correct answer: C. Audio output device

Explanation: Headphones are audio output devices because they convert electrical audio signals from the computer into sound that the user can hear. Thus, option C is correct. Headphones normally do not enter commands like a keyboard, process instructions like a CPU, or store files like a disk. Their principal role is to deliver computer-generated sound privately to the listener.

Correct answer: D. System unit

Explanation: The system unit is the main computer case that houses important internal components such as the motherboard, processor, memory, power supply, and often internal storage. Therefore, option D is correct. A monitor displays information, a keyboard enters text and commands, and speakers produce sound; these are external peripherals rather than the box containing the principal internal parts.

Correct answer: A. Cache memory

Explanation: Cache memory is a small, very fast memory located close to or integrated with the processor. It stores frequently needed instructions and data so the CPU can access them faster than it can access ordinary storage. Hence, option A is correct. A hard disk, optical disc, and pen drive are mainly storage devices with greater capacity but slower access than cache memory.

Correct answer: B. Read Only Memory

Explanation: Read Only Memory, or ROM, is non-volatile memory: it retains its stored contents even when electrical power is removed. Startup or boot instructions stored in ROM help the computer begin its starting process when switched on, so option B is correct. RAM and cache are generally volatile working memories, while a register holds tiny, temporary values inside the processor.

Correct answer: C. Storage device

Explanation: A solid-state drive, or SSD, is a storage component that uses flash memory to retain operating-system files, programs, and user data. It has no moving disks, but its basic purpose is still long-term data storage, so option C is correct. An input device sends data to the computer, an output device presents results, and a communication device connects systems; these are different functions.

Correct answer: D. Optical drive

Explanation: An optical drive uses a laser to read information recorded on optical media such as CDs and DVDs. Therefore, option D is correct. A scanner captures physical images or text, a mouse is a pointing input device, and RAM temporarily holds data for active programs. None of those components is designed to read the laser-based data on a CD or DVD.

Correct answer: A. Video port

Explanation: A monitor receives visual data from the computer through a video port, such as an HDMI, DisplayPort, VGA, or similar display connection. Thus, option A is correct because the port carries picture signals. An audio port carries sound, USB storage refers to data storage rather than a display connection, and a power switch controls electricity instead of transmitting images.

Correct answer: B. Audio port

Explanation: An audio port is designed to carry sound signals. A microphone uses it to send audio into the computer, while headphones use an audio output connection to receive sound from the computer; many computers provide these as separate or combined audio jacks. Therefore, option B is correct. A video port carries picture signals, a printer tray is not a port, and a memory slot holds memory modules.

Correct answer: C. Network port

Explanation: A network port, commonly an Ethernet port, provides the physical connection between a computer and a wired network cable. It allows network data to travel between the computer and devices such as a router or switch, so option C is correct. An audio jack carries sound, a memory slot holds memory modules, and a power button turns the system on or off rather than connecting it to a network.

Correct answer: D. Wireless network adapter

Explanation: A wireless network adapter is a hardware component that sends and receives radio signals for Wi-Fi communication, allowing a computer to join a network without an Ethernet cable. Therefore, option D is correct. A printer produces hard copies, a scanner captures images or text, and a hard disk stores data; none of these primarily provides wireless network access.

Correct answer: A. Processing visual content for the screen

Explanation: A graphics card, or graphics processing unit, processes images, video, and other visual data and sends the resulting display information to the monitor. Thus, option A is correct. Recording sound is handled by audio-input hardware, printing by a printer, and naming files by the operating system or user, so those choices describe different functions.

Correct answer: B. Sound card

Explanation: A sound card is designed to process audio signals entering or leaving a computer. It can work with microphones for input and speakers or headphones for output, so option B is correct. A network card manages data communication over a network, a graphics card handles visual data, and a hard disk stores files rather than processing sound.

Correct answer: C. Buses

Explanation: In computer architecture, buses are shared internal pathways that carry data, addresses, and control signals among the processor, memory, and other components. Therefore, option C is correct. Ports are connection interfaces, folders organize files, and icons are visual symbols used in software interfaces; none of these is the general name for internal data pathways.

Correct answer: D. Power button

Explanation: Pressing the power button sends the command that begins the computer’s startup sequence, so option D is correct. A scroll wheel moves through content, the spacebar inserts a space while typing, and a print key or command is related to printing. The power button should also be distinguished from the power supply unit, which provides electrical power internally.