Basic components of a computer system

Correct answer: A. Clean the barcode and reader surface, then scan again

Explanation: The governing troubleshooting principle is to check simple physical causes before making software or data changes. Dust, smudges, damaged labels, or dirt on the scanner window can interfere with the reflected light pattern and produce an incorrect reading. Therefore, clean the barcode and scanning surface and try again, making option A correct. Driver removal may be considered later; replacing a monitor or deleting records does not solve the scanning cause.

Correct answer: B. OMR reads marks while OCR recognises printed characters

Explanation: The governing concept is the kind of visual information each recognition technology interprets. OMR detects deliberately placed marks, such as shaded bubbles on an answer sheet, and records their positions. OCR analyses printed or handwritten-looking text forms and converts recognised characters into editable digital text. Thus option B is correct. Magnetic cheque characters are handled by MICR, while neither OMR nor OCR is a sound reader or video recorder.

Correct answer: C. It reads special characters printed in magnetic ink quickly and reliably

Explanation: The governing concept is Magnetic Ink Character Recognition. Bank cheques commonly contain specially formed characters printed in magnetic ink along the code line. A MICR reader senses and interprets those characters so banks can capture routing, account, and cheque information quickly and reliably, even during high-volume processing. Therefore, option C is correct. It is not a colour printer, internet connector, or signature generator.

Correct answer: D. It identifies a person using a unique body characteristic

Explanation: The governing concept is the authentication factor used for identity verification. A password is something a user knows, whereas a biometric device measures something the user is, such as a fingerprint, face pattern, or iris feature. Therefore, option D correctly describes the difference. A biometric system does not print data or store electricity, and its purpose is to distinguish individuals rather than give everyone the same identity.

Correct answer: A. The screen can display finer detail

Explanation: The governing concept is display resolution: it describes the number of pixels used to form an image. When resolution increases on a suitable monitor, more pixels can represent objects and text, so finer details and sharper images may be visible. Option A is correct. Speaker loudness, hard-disk capacity, and network strength are separate properties and are not directly changed by monitor resolution.

Correct answer: B. The image may appear less sharp or pixelated

Explanation: The governing concept is the difference between physical screen size and resolution. A large display with too few pixels spreads those pixels over a wider area, reducing pixel density. Consequently, edges, text, and pictures may look less sharp or visibly pixelated, so option B is correct. Screen size alone does not guarantee clarity, and the condition does not cause a printer to stop or reduce RAM.

Correct answer: D. It can produce large precise drawings

Explanation: The governing concept is choosing an output device according to the required format and precision. A plotter is designed to create large, accurate line drawings, such as architectural plans, engineering designs, and maps. Thus option D is correct. A regular office printer is useful for ordinary documents but may not handle very large sheets or precise continuous lines as effectively. The other options describe unrelated functions.

Correct answer: A. It provides fast and relatively clear printing

Explanation: The governing concept is matching printer characteristics to workload. Laser printers use toner and an electrostatic printing process that generally produces fast, consistent, and clear pages, making them suitable for many office documents. Option A is correct. Reading handwriting is an input or recognition task, displaying images is a monitor function, and recording video is unrelated to printing. Print speed and output quality explain the choice.

Correct answer: C. A UPS provides external backup power while a PSU distributes power inside the computer

Explanation: The governing concept is the distinction between backup power and internal power conversion. A UPS supplies temporary external power when the mains supply fails, giving time to save work or shut down safely. A PSU is installed inside the computer and converts incoming electricity into suitable voltages for components such as the motherboard and drives. Therefore option C is correct; the other choices confuse power devices with storage, processing, or networking.

Correct answer: D. Loss of unsaved data and improper system shutdown

Explanation: The governing concept is the protective role of backup power. If electricity fails without a UPS, the computer may switch off immediately. Work that has not been saved can disappear, and an abrupt shutdown may leave files or the operating system in an inconsistent state. Option D is correct. A power cut does not increase monitor size, change keyboard colour, or improve network-card capacity; those choices are unrelated to power protection.

Correct answer: A. Keeping data and results for future use

Explanation: The governing concept is the input-process-output cycle together with storage. Storage retains input data, program instructions, intermediate information, and final results so they can be used later rather than disappearing after processing. Therefore option A is correct. A screen provides visual output, a keyboard or similar device supplies input, and a power unit supplies electricity; none of those functions describes storage. Storage may be temporary or long-term, depending on the device.

Correct answer: B. The result may be wrong because processing used incorrect data

Explanation: The governing concept is the input-process-output principle: the processor follows its instructions and operates on the data it receives. If the input is inaccurate, correct execution can still produce an inaccurate output; this is often summarized as “garbage in, garbage out.” Option B is correct. A CPU does not automatically know the intended value, and incorrect input does not necessarily erase a hard disk or guarantee a correct answer.

Correct answer: D. Running programs need fast working space for the CPU

Explanation: The governing concept is the difference between storage and primary memory. Secondary storage such as an HDD or SSD keeps files for long periods and is useful for backups and photographs, but running programs need fast, directly accessible working memory such as RAM. Therefore, option D is correct. Options A, B, and C describe long-term storage tasks that secondary storage can perform.

Correct answer: A. Check CPU, RAM, and storage use according to the task

Explanation: A performance bottleneck is a component or resource that limits the speed of the entire system. The correct method is to observe CPU, RAM, storage, and, when relevant, graphics usage while the task is running, then compare the readings with the symptoms. Thus option A is correct. Replacing a monitor, deleting files blindly, or switching off speakers does not identify the limiting resource.

Correct answer: B. A slow or heavily used storage device

Explanation: The governing concept is resource-based troubleshooting. If CPU usage is low, the processor is not currently the main limitation, but continuous storage activity indicates that reading, writing, paging, or another disk operation may be delaying the task. Therefore option B is the plausible cause. Monitor resolution, mouse size, and speaker volume do not normally explain sustained storage-related delays.

Correct answer: C. The system may slow because storage is slower than RAM

Explanation: The governing concept is virtual memory or paging. When available RAM is insufficient, the operating system may move some temporary data between RAM and secondary storage. Storage is much slower to access than RAM, so frequent swapping can increase waiting time and make the system sluggish. Thus option C is correct; printer quality and screen brightness are unrelated, and the computer will not always become faster.

Correct answer: D. Compatibility with the processor socket and motherboard support is required

Explanation: The governing concept is hardware compatibility. A processor must physically fit the motherboard socket, and the motherboard must support its electrical requirements, chipset, firmware, memory type, and other platform features. Therefore option D is correct. Printer types, monitor colours, and keyboard languages do not determine whether a processor can be installed. Compatibility must be checked before upgrading a CPU.

Correct answer: A. The expected visual signal may not appear

Explanation: The governing concept is the signal path between the graphics hardware and the display. If the monitor is connected to an inactive or unintended video port, the computer may send the image through another output, so no expected picture may appear on that monitor. Option A is correct. A wrong display connection does not erase RAM, speed up a printer, or normally disable the mouse.

Correct answer: B. Shut down, disconnect power, and use proper static protection

Explanation: The governing concept is safe hardware maintenance. Before opening a computer, shut it down properly, disconnect the power source, and use an antistatic wrist strap or another suitable method to prevent electrostatic discharge. This makes option B correct. Removing a component while powered can cause injury or damage, while renaming files and changing brightness do not protect the hardware during replacement.

Correct answer: C. It can damage sensitive electronic circuits

Explanation: The governing concept is electrostatic discharge, or ESD. A person may carry a charge without noticing it, and touching a circuit board can release that charge suddenly through delicate electronic paths. The discharge may damage or weaken chips and other components, so option C is correct. Static electricity does not change cabinet colour, wet paper, or improve internet speed.

Correct answer: D. Airflow will decrease and components may overheat

Explanation: The governing concept is thermal management in a computer system. Dust blocking the air intake reduces the amount of cool air reaching fans, heat sinks, and internal components. Because heat is removed less effectively, the CPU and other parts may overheat, slow down, or become damaged. Option D is correct; storage capacity, network strength, and automatic printer cleaning are unrelated to airflow.

Correct answer: A. Identify the symptom, check simple connections, test the related component, and verify the result

Explanation: The governing concept is systematic troubleshooting. Begin by identifying the symptom, then inspect simple causes such as loose cables or power connections. Next, test the component most closely related to the symptom, make one justified correction, and verify whether the problem is solved. Therefore option A is correct. Replacing everything, deleting data, or guessing can create new problems and provides no reliable diagnosis.

Correct answer: A. It can retain its instructions even when power is off

Explanation: Volatile memory loses its contents when electrical power is removed, whereas ROM is non-volatile and can retain firmware or startup instructions without continuous power. Therefore, option A is correct. ROM does not store only sound, its location is not defined by being inside the processor, and its capacity is not necessarily larger than RAM; options B, C and D confuse unrelated features.

Correct answer: B. Initial checks may occur, but the operating system will not load

Explanation: Firmware or startup instructions stored in ROM can begin the power-on self-test and search for a bootable operating system. If the storage drive containing that operating system has failed, the early checks may still occur, but the system cannot complete booting or run normal applications. Thus option B is correct; RAM does not become permanent storage, and a monitor cannot create an operating system.

Correct answer: C. Coordinated execution of instructions will be disrupted

Explanation: The ALU performs arithmetic operations and logical comparisons, but the Control Unit fetches instructions, decodes them and coordinates the timing of the CPU’s parts. If the Control Unit fails, the ALU may still be physically functional, yet instructions will not be directed and sequenced properly. Therefore option C is correct; the failure is not limited to a printer or audio output.