Computer Science
कम्प्युटर विज्ञान · Class 8
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chapters done
- Computer Fundamentals
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The syllabus asks for
- Computer: definition; data, information and program; hardware and software
- Working principle of a computer: input, process, output and storage (the IPOS cycle)
- Characteristics of a computer: speed, accuracy, diligence, versatility, storage and automation
- Limitations of a computer and its effects on society
- Uses of computers in Nepal: education, banking, health, communication, agriculture and government
Key points
- A computer (Latin computare, to calculate) is an electronic machine that accepts data, processes it under a program, stores it and gives information.
- Data are raw facts; information is processed, meaningful data. A program is a set of instructions; software is a collection of programs.
- Hardware is the physical, touchable part; software tells it what to do. Neither works without the other.
- IPOS: input devices → CPU (control unit + arithmetic logic unit) → output devices, with storage (RAM temporary, secondary storage permanent) joined to the CPU.
- Characteristics: speed (ms, μs, ns), accuracy (GIGO), diligence, versatility, storage (8 bits = 1 byte, 1024 bytes = 1 KB) and automation.
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The syllabus asks for
- Early calculating devices: abacus, Napier's bones and the slide rule
- Mechanical calculators: Pascaline, Leibniz's stepped reckoner and the Jacquard loom
- Charles Babbage's Difference Engine and Analytical Engine; Ada Lovelace
- Electromechanical and electronic machines: Hollerith's tabulating machine, Mark I, ABC, ENIAC, EDVAC and UNIVAC
- Computers in Nepal: from the census of 2028 BS to today
Key points
- Manual devices: abacus (c. 2700 BC; suanpan: heaven beads 5, earth beads 1), Napier's bones (John Napier, 1617; multiplication), slide rule (William Oughtred, c. 1622; analog).
- Mechanical calculators: Pascaline (Blaise Pascal, 1642; add and subtract, automatic carry), stepped reckoner (Leibniz, 1673; all four operations), Jacquard loom (1804; punched cards as instructions).
- Charles Babbage, father of the computer: Difference Engine (1822) and Analytical Engine (1834) with input cards, mill, store and output. Ada Lovelace wrote the first published program (1843).
- Electromechanical: Hollerith's tabulator (1890 census; IBM, 1924), Harvard Mark I (Aiken and IBM, 1944).
- Electronic: ABC (1942, first electronic digital), ENIAC (1946, first general-purpose; 17,468 tubes), EDVAC (stored program, binary), UNIVAC I (1951, first commercial in the USA).
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The syllabus asks for
- Meaning of a computer generation
- First generation: vacuum tubes
- Second generation: transistors
- Third generation: integrated circuits
- Fourth generation: microprocessors
- Fifth generation: artificial intelligence and parallel processing
Key points
- A generation is a stage of computer development marked by a major new technology, especially a new processing component; each generation is smaller, faster, cheaper, more reliable and more powerful.
- 1st (1946–1958): vacuum tubes, magnetic drums, machine language, milliseconds; huge, hot, unreliable. ENIAC, UNIVAC I.
- 2nd (1958–1964): transistors (Bell Labs, 1947), magnetic core memory, assembly language, FORTRAN and COBOL, microseconds. IBM 1401 (Nepal), IBM 7090.
- 3rd (1964–1975): integrated circuits (Kilby, 1958; Noyce, 1959), keyboards and monitors, time-sharing, BASIC and C, nanoseconds. IBM System/360.
- 4th (1975–present): microprocessors (Intel 4004, 1971; LSI, VLSI, ULSI), PCs, GUI, networks and the Internet. IBM PC, laptops, smartphones.
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The syllabus asks for
- Classification by working principle: analog, digital and hybrid computers
- Classification by size: supercomputer, mainframe, minicomputer and microcomputer
- Microcomputers: desktop, laptop, tablet, smartphone and workstation
- Classification by purpose: general-purpose and special-purpose computers
- Choosing a computer for a task
Key points
- By working principle: analog computers measure continuous data (thermometer, speedometer, slide rule); digital computers count discrete data in 0s and 1s (PC, phone, calculator); hybrid computers do both (ECG, ICU monitor, petrol-pump dispenser).
- By size: supercomputer (fastest; exaflops; weather, research — e.g. LineShine, Frontier), mainframe (thousands of users; banks, airlines — IBM z17), minicomputer (medium, multi-user — PDP-11; now servers), microcomputer (one user; microprocessor; PC).
- Microcomputers: desktop, laptop (notebook), tablet, smartphone and workstation (powerful, for design and video).
- By purpose: general-purpose computers run many programs; special-purpose computers do one job; one built into a machine is an embedded system.
- Choosing a computer depends on the task and software, power, storage, portability, number of users and budget.
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The syllabus asks for
- Software: meaning and importance; how hardware and software work together
- System software: operating system, device drivers, utility programs and language processors
- Application software: packaged and tailor-made software
- Software licences: proprietary, freeware, shareware and open-source software
- Installing, updating and removing software safely
Key points
- Software is a set of programs that tells the hardware what to do; it makes the computer usable, versatile and useful. It works in layers: user → application → operating system → device driver → hardware.
- System software manages the computer: the operating system, device drivers (one for each device), utility programs (antivirus, backup, compression, disk cleanup) and language processors.
- Assembler: assembly → machine code. Compiler: whole program at once, separate file, fast. Interpreter: line by line, stops at the first error.
- Application software does the user's tasks: packaged (ready-made for many users — Word, Chrome, VLC) or tailor-made (built for one organization — a school's result system).
- Licences: proprietary (buy; code secret), freeware (free; code secret), shareware (free trial, then pay), open source (free; code open to change and share). Piracy is illegal.
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The syllabus asks for
- Operating system: meaning and functions
- Types of operating system: single-user and multi-user, CUI and GUI, desktop and mobile
- Common operating systems: Windows, Linux, macOS, Android and iOS
- Working with Windows: desktop, taskbar, Start menu, windows and dialog boxes
- File management: files, folders, paths and extensions; copy, move, rename and delete; Recycle Bin
- Settings: date and time, display, user accounts, installing and removing programs
Key points
- An operating system manages all hardware and software and provides the user interface. Functions: process, memory, file and device management, security, user interface, booting.
- Single-user (one user at a time — Windows 11 Home) vs multi-user (many at once — Linux servers). CUI (typed commands — MS-DOS, Linux terminal) vs GUI (windows, icons, menus, pointer — Windows, Android). Desktop OS (Windows, macOS, Linux) vs mobile OS (Android, iOS).
- Windows (Microsoft, proprietary), Linux (Torvalds 1991, open source; Ubuntu, Fedora), macOS (Apple Macs), Android (Google, Linux-based, most-used mobile OS), iOS (iPhone).
- Windows parts: desktop, icons, taskbar (Start, Search, apps, notification area, clock), Start menu, window (title bar, minimize/maximize/close, scroll bars, status bar), dialog box (tabs, text box, list, check box, option button, OK/Cancel/Apply).
- A file has a name and an extension (.docx, .jpg, .exe); a folder holds files; a path gives the full address, e.g. D:\School\Grade 8\summary.docx.
- Application Software
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The syllabus asks for
- Word processor: features and examples
- Creating, saving, opening and printing a document
- Editing: select, cut, copy, paste, undo, find and replace, spelling and grammar check
- Formatting: font, paragraph, bullets and numbering, page layout, header, footer and page numbers
- Tables, pictures, shapes and WordArt
- Mail merge
Key points
- A word processor creates, edits, formats, saves and prints documents: Microsoft Word, LibreOffice Writer, Google Docs. Features include word wrap, find and replace, spell check, tables, pictures and mail merge.
- Word's window: title bar, Quick Access Toolbar, ribbon (tabs → groups → commands), ruler, document area, insertion point, scroll bars, status bar.
- New Ctrl + N, Open Ctrl + O, Save Ctrl + S (Save As F12 makes a new copy), Print Ctrl + P with copies, pages (1-3, 6) and sides; DOCX for Word, ODT for Writer, PDF for sharing.
- Editing: select, Cut Ctrl + X (move), Copy Ctrl + C, Paste Ctrl + V, Undo Ctrl + Z, Find Ctrl + F, Replace Ctrl + H (match case, whole words), spelling and grammar F7.
- Formatting: font, size (points), bold/italic/underline; alignment (Ctrl + L/E/R/J), line spacing, indents; bullets and numbering; margins (Normal 2.54 cm), orientation, A4 size; header (top), footer (bottom), page numbers (Insert → Page Number).
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The syllabus asks for
- Spreadsheet: workbook, worksheet, row, column, cell, cell address and range
- Entering and editing data; data types; AutoFill
- Formulas and operators; relative and absolute cell references
- Functions: SUM, AVERAGE, MAX, MIN, COUNT and IF
- Formatting cells; sorting and filtering data
- Charts: column, bar, line and pie
Key points
- A spreadsheet (Excel, Calc, Google Sheets) calculates with data in rows and columns. A workbook (.xlsx, .ods) holds worksheets; a cell is where a row (number) meets a column (letter); its address is like C5; a range is written B2:E6 and has columns × rows cells.
- Data types: text (left), numbers (right), currency, percentage, dates, formulas, TRUE/FALSE. Errors: #####, #DIV/0!, #NAME?, #VALUE!, #REF!. AutoFill with the fill handle copies or continues series.
- Formulas start with =; operators + - * / ^ %, comparisons = <> > < >= <=, &; brackets first, then ^, then × ÷, then + −.
- Relative references (B2) change when copied; absolute (B1) do not; mixed B1, B1; F4 toggles.
- Functions: SUM, AVERAGE, MAX, MIN, COUNT (numbers only), IF(condition, if_true, if_false); nested IF for grades.
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The syllabus asks for
- Presentation software: features and examples
- Creating a presentation: slides, layouts, themes and placeholders
- Inserting text, pictures, tables, charts, audio and video
- Transitions and animations
- Slide views, the slide master and running a slide show
- Designing an effective presentation
Key points
- Presentation software (PowerPoint, Impress, Google Slides, Keynote, Canva) creates and shows slides; files are .pptx or .odp.
- A layout arranges placeholders on a slide (Title Slide, Title and Content, Two Content, Comparison, Title Only, Picture with Caption); a theme designs all slides; a placeholder holds a title, text or object.
- New slide Ctrl + M; insert pictures, tables, charts, audio and video from the Insert tab; the Playback tab sets how audio and video start.
- A transition works between slides (Transitions tab, Apply To All, Advance After); an animation works on objects (entrance, emphasis, exit, motion paths; On Click, With Previous, After Previous).
- Views: Normal, Outline, Slide Sorter, Notes Page, Reading View, Slide Show. The slide master changes every slide at once.
- Web, Communication and Society
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The syllabus asks for
- World Wide Web: web page, website, web browser, URL and HTML
- Structure of an HTML document: html, head, title and body
- Formatting tags: headings, paragraphs, line breaks, bold, italic, underline and font
- Lists, images and hyperlinks
- Tables in HTML
- Creating and viewing a small website
Key points
- The WWW (Tim Berners-Lee, CERN, 1989–1991) is a collection of linked web pages on web servers, opened over the Internet with a browser. A web page is one HTML document; a website is related pages under one domain; the home page is index.html.
- URL (Uniform Resource Locator) = protocol (https://) + domain name (www.name.edu.np) + path + file name. HTTP(S) is the transfer protocol.
- HTML (HyperText Markup Language, now HTML5) uses tags in angle brackets: container tags <p>…</p>, empty tags <br>, <hr>, <img>; attributes go in the opening tag: name="value".
- Structure: <!DOCTYPE html>, <html>, <head> with <title> (shown on the tab), <body> (shown in the window). Close tags in reverse order.
- Formatting: <h1>–<h6>, <p>, <br>, <hr>, <b>, <i>, <u>, <sup>, <sub>, <font face size color> (old; CSS today), align.
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The syllabus asks for
- ICT: meaning, components and uses
- Communication technologies: telephone, mobile, radio, television, satellite and the internet
- Internet services: WWW, e-mail, search engines, chat, video conferencing and cloud storage
- ICT in Nepal: e-governance, online banking and digital payments, e-learning
- Advantages and disadvantages of ICT; the digital divide
Key points
- ICT is the use of computers, telecommunication equipment, networks and software to collect, store, process, send and receive information.
- Its six components are hardware, software, data, network, people and procedures.
- Communication technologies: telephone (voice over wire), mobile (radio waves to the tower of each cell), radio (one-way sound), television (one-way pictures and sound), satellite (uplink and downlink; geostationary at about 35,786 km) and the Internet (a network of networks that carries everything).
- Nepal's milestones: Radio Nepal 1951, NTV 1985, e-mail 1994, first ISP 1995, GSM mobile 1999, 4G 2017, NepaliSat-1 2019, Nagarik App 2021.
- Internet services: WWW (linked web pages; not the same as the Internet), e-mail (To, Cc, Bcc, attachment), search engines, chat, video conferencing and cloud storage.
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The syllabus asks for
- Computer ethics: meaning and the Ten Commandments of computer ethics
- Cyber crime: hacking, phishing, cyber bullying, identity theft and software piracy
- Intellectual property, copyright and plagiarism
- Cyber law in Nepal: the Electronic Transactions Act, 2063
- Digital citizenship and safe use of social media
Key points
- Computer ethics are the moral rules for using computers; laws are enforced by the state. Every cyber crime is unethical, but not every unethical act is a crime.
- The Ten Commandments (Computer Ethics Institute, 1992): do not harm, interfere, snoop, steal, lie, copy paid software, use others' resources or take others' work; think about society; respect others.
- Cyber crime is any illegal act done with a computer or the Internet: hacking, phishing, cyber bullying, identity theft, software piracy, online fraud.
- Intellectual property is protected by copyright, patents, trademarks and designs. In Nepal copyright lasts for the author's life plus 50 years (Copyright Act, 2059); plagiarism is using work without credit.
- Nepal's cyber law is the Electronic Transactions Act, 2063, authenticated 22 Mansir 2063 (8 December 2006): 12 chapters, 80 sections, offences in sections 44–59.
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The syllabus asks for
- Computer virus: meaning, history and how it spreads
- Types of malware: virus, worm, Trojan horse, spyware, adware and ransomware
- Symptoms of an infected computer
- Antivirus software: how it works and examples
- Protecting a computer: safe browsing, updates, backups and strong passwords
Key points
- A computer virus is a harmful program that attaches itself to files, copies itself when the file is run, and damages data without the user's knowledge; malware is the general name for all harmful programs.
- History: Creeper (1971), Elk Cloner (1982), the name "computer virus" by Fred Cohen (1983–84), Brain from Lahore (1986, first PC virus), Morris worm (1988), ILOVEYOU (2000), WannaCry (2017).
- Viruses spread through pen drives, pirated software, e-mail attachments, fake links and apps, and networks.
- Types: virus (needs a host; boot sector, file, macro, multipartite), worm (spreads by itself over networks), Trojan horse (disguised as useful), spyware (secretly watches; keyloggers), adware (unwanted adverts), ransomware (locks files for money).
- Symptoms: slowness, crashes, missing or locked files, shortcut folders on pen drives, pop-ups, a disabled antivirus, messages sent without you.
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The syllabus asks for
- Computer network: meaning, advantages and disadvantages
- Network components: server, client, NIC, cables, hub, switch, router and modem
- Transmission media: wired and wireless
- Types of network: LAN, MAN and WAN
- Network topology: bus, ring and star
- The internet as a network of networks
Key points
- A computer network is two or more computers and devices connected by wired or wireless media to share data, hardware, software and an Internet connection; every device on it is a node, and all follow protocols.
- Advantages: sharing hardware, data and one Internet line; fast communication; central control and backup. Disadvantages: cost and skill, fast spread of viruses, security risk, dependence on the server or switch.
- Components: server (provides services), client (uses them), NIC (with a 48-bit MAC address), cables, hub (copies to all ports), switch (sends only to the destination port, by MAC address), router (joins networks, by IP address), modem (digital ↔ analog; ONT on fibre), Wi-Fi access point.
- Wired media: twisted pair (UTP, RJ-45, 100 m), coaxial (cable TV), optical fibre (light, fastest, many km). Wireless media: radio and Wi-Fi, Bluetooth (about 10 m), microwave (line of sight), satellite, infrared.
- LAN (building, up to about 1 km, fastest), MAN (city or valley), WAN (country or world; the Internet); PAN (one person, about 10 m). WLAN is a wireless LAN, not a WAN.
- Number System, Graphics and Multimedia
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The syllabus asks for
- Number systems: decimal, binary, octal and hexadecimal
- Converting decimal numbers to binary, octal and hexadecimal
- Converting binary, octal and hexadecimal numbers to decimal
- Converting between binary, octal and hexadecimal
- Bits, bytes and the units of memory
Key points
- A number system writes numbers with a fixed set of digits; its base (radix) is the number of digits, and the largest digit is base − 1. Binary (2: 0, 1), octal (8: 0–7), decimal (10: 0–9), hexadecimal (16: 0–9, A–F with A = 10 … F = 15). Always write the base: (101)2.
- All four are positional: place values are powers of the base, starting with base^0 = 1 at the right.
- Computers use binary because their switches have two states (off/on); octal (3 bits per digit) and hexadecimal (4 bits per digit) are short ways of writing binary — hex is used for colour codes and MAC addresses.
- Decimal → any base: divide by the base until the quotient is 0; read the remainders from the bottom up; write 10–15 as A–F.
- Any base → decimal: multiply each digit by its place value and add.
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The syllabus asks for
- Computer graphics: meaning and uses
- Raster and vector graphics
- Graphics software: Paint, GIMP, Inkscape and Canva
- Drawing and editing a picture
- Image file formats: BMP, JPEG, PNG, GIF and SVG
Key points
- Computer graphics are pictures, drawings, charts and animations made, stored, edited and shown by computer; they may be 2D or 3D, interactive or non-interactive. Uses: design, advertising, entertainment, education, CAD, maps, medicine, charts and the GUI.
- Raster (bitmap) graphics are grids of pixels; resolution is width × height in pixels; colour depth n bits gives 2^n colours (24-bit = 16,777,216). Uncompressed size = width × height × bits ÷ 8 bytes.
- Each pixel's colour is a mix of red, green and blue, each 0–255.
- Vector graphics store shapes as numbers and stay sharp at any size; raster pictures pixelate when enlarged.
- Paint (raster, with Windows), GIMP (free raster editor, XCF, layers), Inkscape (free vector editor, SVG) and Canva (online templates, free and Pro plans).
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The syllabus asks for
- Multimedia: meaning and elements (text, graphics, audio, video and animation)
- Multimedia hardware and software
- Uses of multimedia in education, entertainment, business and health
- Advantages and disadvantages of multimedia
Key points
- Multimedia is the combined use of two or more media — text, graphics, audio, video and animation — usually with a computer.
- Video is recorded from real life with a camera; animation is drawn or computer-made pictures shown quickly (about 12–30 a second) so they seem to move.
- Linear multimedia plays in a fixed order (a film); interactive multimedia responds to the user (E-Paath, games, websites).
- Hardware: input — microphone, webcam, camera, scanner, graphics tablet; output — monitor, speakers, headphones, projector; inside — CPU, RAM, graphics card, sound card; storage — SSD, hard disk, memory card, cloud.
- Software: VLC (player), Audacity (audio), OpenShot, Kdenlive and CapCut (video), Pencil2D and Blender (animation), GIMP and Inkscape (graphics), PowerPoint (presentation).
- Programming
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The syllabus asks for
- Program and programming; steps of program development
- Algorithm: meaning, features and writing algorithms
- Flowchart: symbols, rules and drawing flowcharts
- Sequence, selection and repetition in algorithms and flowcharts
- Pseudocode
Key points
- A program is a set of instructions in a programming language; programming is planning, writing, testing and correcting programs.
- The program development life cycle: problem analysis (input, process, output), program design, coding, testing and debugging, documentation, implementation and maintenance.
- An algorithm is a finite set of clear step-by-step instructions from Start to Stop; a good one has input, output, definiteness, finiteness and effectiveness.
- A flowchart draws an algorithm with standard symbols: oval (start/stop), parallelogram (input/output), rectangle (process), diamond (decision), arrows (flow lines), circle (connector).
- Flowchart rules: one Start and one Stop, top to bottom, arrows on every line, two labelled exits on every decision, no crossing lines.
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The syllabus asks for
- Programming languages: low-level (machine and assembly) and high-level languages
- Language processors: compiler, interpreter and assembler
- Syntax errors, logical errors and run-time errors; testing and debugging
- Common high-level languages: Python, C and Java
- Constants, variables and data types
Key points
- A programming language is a set of words, symbols and rules (syntax) for writing instructions for a computer.
- Low-level languages: machine language (binary; runs directly; machine-dependent) and assembly language (mnemonics such as MOV and ADD; needs an assembler). High-level languages (Python, C, Java) are English-like and portable.
- Language processors turn source code into object code: a compiler translates the whole program at once and makes an object program; an interpreter translates and runs one line at a time; an assembler translates assembly language.
- Syntax error: breaking the rules of the language. Run-time error: an impossible operation while running, such as division by zero. Logical error: wrong method, wrong output, no message.
- Testing runs a program with test data of known answers; debugging finds and corrects errors (error messages, dry runs, printing values, stepping with IDLE's debugger, breakpoints).
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The syllabus asks for
- Python: features, installing Python, IDLE and the two modes (interactive and script); the first program
- Character set, keywords, identifiers, comments, constants, variables and data types (int, float, str, bool)
- Operators and expressions: arithmetic, relational, logical and assignment; order of operations
- Input and output: print() with sep and end, input(), type conversion and f-strings
- Built-in functions and the math module; string indexing, slicing and methods
- Selection: if, if...else, if...elif...else and nested if
- Loops: for with range(), while, break and nested loops
- Writing, running and debugging simple programs: syntax, run-time and logical errors; trace tables
Key points
- Python (Guido van Rossum, 1991) is an easy, interpreted, case-sensitive language in which indentation matters. Programs are written in IDLE's editor, saved as .py and run with F5; the Shell's >>> prompt carries out one line at a time.
- Character set: letters, digits, special characters and white space. Keywords have a fixed meaning and cannot be names. Identifiers use letters, digits and _, do not start with a digit, contain no spaces or special characters and are case-sensitive. A comment starts with #.
- A variable is created by assignment (x = 5) and can change; a constant is written in capitals by custom. The basic data types are int, float, str and bool; type() shows a value's type.
- Operators: arithmetic (+ - * / // % ), relational (== != > < >= <=), logical (and or not) and assignment (= += -= = /=). Order: brackets, , / // %, + -, comparisons, not, and, or. ^ is not power.
- Output: print() with sep and end; \n and \t; f-strings with {value:.2f}. Input: input() always returns text, so convert it with int() or float().
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Objective questions
Computer Science: Unit-wise Objective Question Bank
Subjective questions
Computer Science: Unit-wise Subjective Question Bank
Model sets and predicted questions
Computer Science: Model Question Sets and Predicted Questions
Exam guide
The Basic Level Examination: Pattern, Grid and Strategy
The paper
School annual examination, 2 hr, FM 50 written (+ practical)
| Section | Questions | Marks each | Total |
|---|---|---|---|
| Group A objective | 10 | 1 | 10 |
| Group B short | 10 | 2 | 20 |
| Group C long | 5 | 4 | 20 |