About this quiz
CPU, memory types, units, storage, booting and troubleshooting.
This Lok Sewa practice set has 50 multiple-choice questions (Subject: Computer · For: Computer Operator · Level: Medium). Take the quiz above first; after that, use the study list below to revise every question with its correct answer and a short explanation.
Study list: all 50 questions with answers and explanations
ALU stands for:
- A) Arithmetic Load Unit
- B) Array Logic Unit
- C) Automatic Logic Unit
- D) Arithmetic Logic Unit ✔
Why: ALU is the Arithmetic Logic Unit, the part of the CPU that does calculations (add, subtract) and logical comparisons (greater than, equal to).
The part of the CPU that directs and coordinates operations is the:
- A) Control Unit ✔
- B) ALU
- C) Register
- D) Cache
Why: The Control Unit (CU) fetches instructions, decodes them and tells the ALU, memory and input/output devices what to do and when.
The fastest memory in a computer is:
- A) RAM
- B) Registers ✔
- C) Hard disk
- D) Cache on the hard disk
Why: Registers are tiny storage locations inside the CPU itself, so they are the fastest memory. They hold the data the CPU is working on right now.
The main circuit board of a computer is the:
- A) Daughter card
- B) Hard disk
- C) Motherboard ✔
- D) SMPS
Why: The motherboard is the main circuit board. The CPU, RAM, storage, power supply and expansion cards all connect to it.
SMPS converts:
- A) DC to AC
- B) Analog to digital signals
- C) Data to information
- D) AC mains to low-voltage DC ✔
Why: The SMPS (Switched-Mode Power Supply) converts AC mains electricity (230 V in Nepal) into low-voltage DC (such as 12 V, 5 V, 3.3 V) for computer parts.
RAM is called volatile because:
- A) Data is lost when power is off ✔
- B) It is very fast
- C) It is permanent
- D) It is read-only
Why: RAM needs power to keep its data, so everything in it is lost when the computer is switched off. That is why you must save your work.
Which memory is non-volatile?
- A) RAM
- B) ROM ✔
- C) Cache
- D) Registers
Why: ROM is non-volatile: it keeps its data without power. It stores firmware such as the BIOS.
SRAM is mainly used as:
- A) Hard disk
- B) Optical storage
- C) Cache memory ✔
- D) Virtual memory
Why: SRAM (Static RAM) is very fast but costly, so it is used for the CPU's cache memory rather than main memory.
Main memory (RAM sticks) usually uses:
- A) SRAM
- B) EPROM
- C) PROM
- D) DRAM ✔
Why: Main memory uses DRAM (Dynamic RAM), which is cheaper and holds more data per chip, but must be refreshed constantly.
EPROM can be erased using:
- A) Ultraviolet light ✔
- B) Electric signals only
- C) A magnet
- D) Formatting
Why: EPROM (Erasable Programmable ROM) is erased by shining ultraviolet light through a small window on the chip, then it can be reprogrammed.
EEPROM is erased:
- A) With UV light
- B) Electrically ✔
- C) By heat
- D) It cannot be erased
Why: EEPROM (Electrically Erasable Programmable ROM) is erased and rewritten with electrical signals, without removing the chip.
Flash memory used in pen drives is a type of:
- A) PROM
- B) SRAM
- C) EEPROM ✔
- D) Magnetic tape
Why: Flash memory is a fast type of EEPROM that erases in blocks. It is used in pen drives, memory cards and SSDs.
Memory between the CPU and RAM that speeds up access is:
- A) Virtual memory
- B) ROM
- C) Hard disk
- D) Cache ✔
Why: Cache memory sits between the CPU and RAM and holds frequently used data, so the CPU waits less.
Using part of the hard disk as extra RAM is called:
- A) Virtual memory ✔
- B) Cache memory
- C) Flash memory
- D) Buffer
Why: Virtual memory uses part of the hard disk (the page file) as extra RAM when real RAM is full. It is much slower than real RAM.
Which order is from fastest to slowest?
- A) RAM, cache, registers, hard disk
- B) Registers, cache, RAM, hard disk ✔
- C) Hard disk, RAM, cache, registers
- D) Cache, hard disk, RAM, registers
Why: Speed falls (and size grows) from registers → cache → RAM → hard disk. Registers are inside the CPU, and the hard disk is the slowest.
1 byte equals:
- A) 4 bits
- B) 16 bits
- C) 8 bits ✔
- D) 1024 bits
Why: 1 byte = 8 bits. A bit is a single 0 or 1, and one byte can store one character such as 'A'.
A nibble equals:
- A) 8 bits
- B) 2 bits
- C) 16 bits
- D) 4 bits ✔
Why: A nibble is 4 bits, which is half a byte.
1 KB equals:
- A) 1024 bytes ✔
- B) 1000 bits
- C) 1024 bits
- D) 100 bytes
Why: In computer memory, 1 kilobyte (KB) = 1,024 bytes (2¹⁰), not exactly 1,000.
1 GB equals:
- A) 1000 KB
- B) 1024 MB ✔
- C) 1024 KB
- D) 1024 TB
Why: 1 gigabyte (GB) = 1,024 megabytes (MB). The order is byte → KB → MB → GB → TB → PB, each 1,024 times the previous.
Which is the largest?
- A) Terabyte
- B) Gigabyte
- C) Petabyte ✔
- D) Megabyte
Why: A petabyte (PB) = 1,024 TB, so it is larger than a terabyte, gigabyte or megabyte.
1 TB equals:
- A) 1024 MB
- B) 1000 MB
- C) 1024 PB
- D) 1024 GB ✔
Why: 1 terabyte (TB) = 1,024 GB. Many hard disks today are 1 TB or more.
Magnetic tape provides which type of access?
- A) Sequential ✔
- B) Random
- C) Direct
- D) Parallel
Why: Magnetic tape is read in order from start to end (sequential access), so finding data in the middle is slow. It is used for backups.
A hard disk is a:
- A) Optical storage device
- B) Magnetic storage device ✔
- C) Volatile memory
- D) Input device
Why: A hard disk stores data magnetically on spinning metal platters, read and written by moving heads.
CD and DVD are:
- A) Magnetic storage
- B) Primary memory
- C) Optical storage ✔
- D) Flash memory
Why: CDs and DVDs are optical storage: a laser reads tiny pits on the disc's surface.
A single-layer DVD typically holds:
- A) 700 MB
- B) 25 GB
- C) 1.44 MB
- D) 4.7 GB ✔
Why: A single-layer DVD holds about 4.7 GB, about seven times a CD. A dual-layer DVD holds about 8.5 GB.
A typical CD holds about:
- A) 700 MB ✔
- B) 4.7 GB
- C) 25 GB
- D) 1 TB
Why: A standard CD holds about 700 MB of data, or about 80 minutes of audio.
A single-layer Blu-ray disc holds:
- A) 4.7 GB
- B) 25 GB ✔
- C) 700 MB
- D) 1.44 MB
Why: A single-layer Blu-ray disc holds 25 GB. Its blue-violet laser has a shorter wavelength, so it can read smaller pits than a DVD's red laser.
Which storage has no moving parts?
- A) Hard disk
- B) Floppy disk
- C) SSD ✔
- D) Magnetic tape
Why: An SSD (Solid State Drive) uses flash memory chips with no moving parts, so it is faster, quieter and more shock-resistant than a hard disk.
Hard disk rotation speed is measured in:
- A) MHz
- B) DPI
- C) PPM
- D) RPM ✔
Why: Hard disk speed is measured in RPM (revolutions per minute), commonly 5,400 or 7,200 RPM. Higher RPM means faster data access.
The process of starting a computer and loading the OS is:
- A) Booting ✔
- B) Formatting
- C) Compiling
- D) Scanning
Why: Booting is starting the computer: the BIOS/UEFI checks the hardware and then loads the operating system into RAM.
Starting a computer from the power-off state is:
- A) Warm boot
- B) Cold boot ✔
- C) Soft reset
- D) Hibernation
Why: A cold boot starts the computer from fully off, by pressing the power button.
Restarting an already running computer is:
- A) Cold boot
- B) POST
- C) Warm boot ✔
- D) Shutdown
Why: A warm boot restarts a computer that is already on, for example with Restart or Ctrl + Alt + Del, without cutting power.
BIOS stands for:
- A) Binary Input Output Setup
- B) Basic Internal Operating System
- C) Boot Input Output Software
- D) Basic Input Output System ✔
Why: BIOS stands for Basic Input Output System. It starts and checks the hardware and then hands over to the operating system.
BIOS is stored in:
- A) ROM or flash on the motherboard ✔
- B) RAM
- C) The hard disk only
- D) Cache
Why: The BIOS is firmware stored in a ROM or flash chip on the motherboard, so it is there even when the computer is off.
The hardware check run at startup is called:
- A) BOOT-CHECK
- B) POST ✔
- C) SCANDISK
- D) FORMAT
Why: POST (Power-On Self Test) checks the CPU, RAM, keyboard and other basic hardware at startup. Problems are shown as beep codes or messages.
BIOS settings and the system clock are kept by the:
- A) Cache
- B) SMPS
- C) CMOS ✔
- D) GPU
Why: CMOS is a small memory that stores BIOS settings and the clock. A small battery on the motherboard keeps it powered.
If a computer shows the wrong date and time after every start, the likely cause is:
- A) A faulty mouse
- B) A full hard disk
- C) A virus in Word
- D) A weak CMOS battery ✔
Why: When the CMOS battery is weak, the clock and BIOS settings reset each time the computer is unplugged. Replacing the coin battery fixes it.
A computer beeps and shows no display. The first part to check is:
- A) RAM ✔
- B) Mouse
- C) Speakers
- D) Keyboard
Why: Beeps with no display often mean the RAM is loose or faulty. Reseating or cleaning the RAM sticks is the first step.
The newer replacement for BIOS is:
- A) CMOS
- B) UEFI ✔
- C) POST
- D) SMPS
Why: UEFI (Unified Extensible Firmware Interface) is the modern replacement for BIOS, with faster booting, support for large disks and Secure Boot.
The shortcut to open Task Manager directly is:
- A) Ctrl+Alt+Tab
- B) Alt+F4
- C) Ctrl+Shift+Esc ✔
- D) Ctrl+P
Why: Ctrl + Shift + Esc opens Task Manager directly. Ctrl + Alt + Del opens a security screen from which Task Manager can be chosen.
Ending a program that is not responding is done from:
- A) Control Panel fonts
- B) Paint
- C) Notepad
- D) Task Manager ✔
Why: In Task Manager, select the frozen program and click End task to close it without restarting the computer.
Rearranging scattered file pieces on a hard disk is called:
- A) Defragmentation ✔
- B) Formatting
- C) Partitioning
- D) Compression
Why: Defragmentation puts the scattered pieces of files back together on a hard disk, so it reads faster. SSDs do not need it.
A tool that removes temporary files to free space is:
- A) Defragmenter
- B) Disk Cleanup ✔
- C) BIOS setup
- D) Device Manager
Why: Disk Cleanup removes temporary files, the Recycle Bin contents and other unneeded files to free disk space.
A device that gives backup power during a power cut is:
- A) SMPS
- B) Modem
- C) UPS ✔
- D) Router
Why: A UPS (Uninterruptible Power Supply) has a battery that keeps the computer running for a short time during a power cut, so you can save and shut down.
The message 'Operating system not found' often means:
- A) Low printer ink
- B) Monitor cable loose
- C) Keyboard not working
- D) Wrong boot order or failed hard disk ✔
Why: This usually means the BIOS is trying to boot from the wrong drive (boot order) or the hard disk with the OS has failed or is disconnected.
Device drivers are installed to:
- A) Let the OS communicate with hardware ✔
- B) Increase RAM size
- C) Repair the screen
- D) Speed up the internet
Why: A driver is software that lets the operating system talk to a hardware device, such as a printer or graphics card.
A blue screen error in Windows is usually caused by:
- A) Low brightness
- B) Driver or hardware faults ✔
- C) A full recycle bin
- D) Wrong wallpaper
Why: A blue screen (BSOD) is a serious system error, often caused by a faulty driver, bad RAM or other hardware problems.
A card used to connect a computer to a LAN is a:
- A) GPU
- B) Sound card
- C) NIC ✔
- D) TV card
Why: A NIC (Network Interface Card) connects the computer to a network, usually through an RJ-45 Ethernet port or Wi-Fi.
The component that processes images for the display is the:
- A) SMPS
- B) NIC
- C) ROM
- D) GPU ✔
Why: The GPU (Graphics Processing Unit) processes images and video for the monitor, and handles graphics-heavy work like games.
A very slow computer is best improved first by:
- A) Removing unneeded startup programs and scanning for malware ✔
- B) Changing the wallpaper
- C) Increasing screen brightness
- D) Unplugging the mouse
Why: Too many startup programs and malware are common causes of slowness. Removing unneeded startup programs and scanning for viruses are the first, free fixes.