Computer Science: Unit-wise Subjective Question Bank

1. Data are raw, unprocessed facts and figures, such as the marks 72, 85 and 90 of a student. Information is data processed into a meaningful form, such as "total 247, average 82.33, grade A".

2. GIGO means Garbage In, Garbage Out: if the input data or instructions are wrong, the output is wrong too. A computer cannot notice that its input is wrong, because it has no intelligence of its own; it only follows instructions.

3. Any two: it has no intelligence (IQ) and cannot think for itself; it has no feelings; it needs a program for every task; it needs correct input; it cannot work without electricity.

4. Banking: keeping customer accounts, ATMs, mobile and internet banking, digital payments such as eSewa and Khalti. Health: keeping patient records, X-ray and CT scanning, online appointments, telemedicine.

5. Speed: a computer does millions of operations in a second, timed in microseconds and nanoseconds. Accuracy: given correct input and program, its results are correct (GIGO). Diligence: it works for hours without getting tired or bored. Versatility: it can do many kinds of work — typing, calculating, drawing, playing music. (Storage and automation are also accepted.)

6. Positive: faster work and better services in banks and offices; easy communication and learning through the Internet. Negative: some jobs are lost to machines; health problems from long use, cyber crime and addiction to games and social media.

1. An abacus is the oldest calculating device, a frame with beads on rods, used from about 2700 BC. It is used for counting, adding and subtracting by moving the beads; the Chinese suanpan has heaven beads worth 5 and earth beads worth 1.

2. Napier's bones were a set of numbered rods (strips) used for multiplication, by reading and adding the numbers on the rods placed side by side. They were invented by the Scottish mathematician John Napier in 1617.

3. The Pascaline (Blaise Pascal, 1642) used toothed wheels with automatic carry and could only add and subtract. The stepped reckoner (Gottfried Leibniz, 1673) could do all four operations: add, subtract, multiply and divide.

4. In 1804 Joseph Marie Jacquard's loom used punched cards to control the pattern woven into cloth. It was the first machine controlled by stored instructions on cards — the idea Babbage used for the Analytical Engine and Hollerith for his tabulator.

5. ENIAC (Electronic Numerical Integrator and Computer), 1946: the first general-purpose electronic digital computer, built in the USA with 17,468 vacuum tubes; it was huge, used a lot of electricity and was programmed by setting switches and cables. UNIVAC I (Universal Automatic Computer), 1951: the first computer sold commercially in the USA; it used vacuum tubes and magnetic tape and processed the US census.

6. (1) In 2028 BS (1971 AD) an IBM 1401, a second-generation computer, was brought to Nepal on rent (Rs 1,25,000 a month) to process the census of 2028 BS. (2) In 2031 BS the Electronic Data Processing Centre was set up; it later became the National Computer Centre (NCC). (3) In 2038 BS the ICL 2950/10 mainframe, with 64 terminals, came for the census of 2038 BS. (4) From 2039–2040 BS microcomputers such as Apple were imported by private companies; the Internet came in 2052 BS (1995), and today computers are used in every bank, office and school.

1. Any two: they used vacuum tubes; they were huge, heavy and gave off great heat; they used a lot of electricity and failed often; they were programmed in machine language; their speed was measured in milliseconds.

2. A transistor is a small electronic switch made of a semiconductor (invented at Bell Labs in 1947). Compared with a vacuum tube, it is far smaller, uses less electricity, gives off less heat and is more reliable.

3. An integrated circuit (IC, or chip) is a small piece of silicon on which many transistors and other components are made together. ICs were first used in the third generation (about 1964–1975).

4. A microprocessor is a single chip that contains the whole CPU of a computer. The first was the Intel 4004, made in 1971.

5.

6. (1) Technology: artificial intelligence (AI) — computers that learn, reason and understand language — and parallel processing, in which many processors work on parts of a problem at the same time. (2) Features: they can understand natural (spoken and written) language, recognise faces and speech, and learn from data. (3) Uses: voice assistants, translation apps, self-driving cars, medical diagnosis, robots. (4) Research continues in quantum computing; this generation is still developing.

1. A supercomputer is the fastest and most powerful kind of computer, with thousands of processors working in parallel. Uses: weather forecasting, scientific research, space and nuclear studies, designing medicines.

2. Mainframes serve thousands of users at the same time, so they are used by banks for customer accounts and by airlines and railways for ticket booking (also by governments for census and tax records).

3. A desktop is designed to stay on a desk, with a separate monitor, keyboard and system unit, and is cheaper and easier to upgrade. A laptop has the screen, keyboard and battery in one portable unit, so it can be carried and used without mains power.

4. Special-purpose computers are made to do only one particular task; when built into a machine they are called embedded systems. Examples: the computer in a washing machine, a traffic-light controller, an ATM, a digital camera.

5. Supercomputer: the fastest and most expensive; used for weather and research. Mainframe: large, very powerful, used by thousands of users at once in banks and airlines. Minicomputer: medium-sized and multi-user, used by smaller organisations; today's servers do this job. Microcomputer: a computer built around a microprocessor for one user, such as a desktop, laptop, tablet or smartphone.

6. (a) A mainframe (or powerful servers), because thousands of branch users must reach the same accounts at once. (b) A supercomputer, because forecasting needs huge numbers of calculations very fast. (c) A microcomputer — a desktop or laptop — which is cheap and enough for one user. (d) A workstation, a powerful microcomputer with a fast processor and graphics card for design and animation.

1. A device driver is a small program that lets the operating system communicate with one particular hardware device, such as a printer, webcam or graphics card. Without the right driver the device does not work, or works badly.

2. Utility programs are system programs that maintain, protect and tidy the computer. Examples: antivirus, backup software, file compression (WinRAR, 7-Zip), Disk Cleanup.

3. Packaged software is ready-made for many users and sold or given in the market, such as MS Office or VLC. Tailor-made (customised) software is built for the needs of one organisation, such as a school's result system or a bank's account system.

4. Freeware can be used free of cost for ever, but its source code is not given (for example Google Chrome, Adobe Acrobat Reader). Shareware can be tried free for a limited time or with limited features, after which the user must pay (for example WinRAR's trial).

5. Operating system: manages all hardware and software and provides the user interface (Windows, Linux). Device drivers: let the OS control each device. Utility programs: maintain and protect the computer (antivirus, backup, compression). Language processors: translate programs into machine code — assembler, compiler and interpreter.

6. Proprietary software is owned by a company; users buy a licence to use it, and the source code is secret and may not be changed or shared (MS Windows, MS Office, Adobe Photoshop). Open-source software is free to use, and its source code is open for anyone to study, change and share (Linux, LibreOffice, GIMP, Firefox). Piracy — copying or using software without a licence — is wrong because it is theft of the makers' work, it is a crime, and pirated copies often carry viruses.

1. In a CUI (character user interface) the user types commands, as in MS-DOS or the Linux terminal; it needs commands to be remembered. In a GUI (graphical user interface) the user clicks windows, icons, menus and buttons with a mouse or a finger, as in Windows or Android; it is easy for beginners.

2. A file extension is the part of a file name after the dot that shows the type of file. Examples: .docx — a Word document; .jpg — a photograph; .mp3 — a sound file; .exe — a program (any two).

3. Copying makes a duplicate in the new place and leaves the original where it was (Ctrl + C, then Ctrl + V). Moving takes the file to the new place and removes it from the old one (Ctrl + X, then Ctrl + V).

4. The Recycle Bin is a folder where Windows keeps files deleted from the hard disk, so that they can be recovered. To restore a file, open the Recycle Bin, select the file and click Restore; it returns to its old folder. (Files deleted with Shift + Delete, or from a pen drive, skip the Recycle Bin.)

5. A single-user OS lets one person use the computer at a time (Windows 11 Home). A multi-user OS lets many users work on it at the same time, usually over a network (Linux servers, UNIX). A desktop OS runs on desktops and laptops (Windows, macOS, Linux). A mobile OS runs on smartphones and tablets and is designed for touch screens (Android, iOS).

6. Path: D:\School\Grade 8\report.docx (1 mark). Create a folder: right-click in the empty area → New → Folder, type a name and press Enter. Rename: select the file, press F2 (or right-click → Rename), type the new name and press Enter. Delete: select the file and press Delete; it goes to the Recycle Bin (3 marks).

1. Any four: typing and editing text; formatting text and paragraphs; spelling and grammar checking; inserting tables, pictures and shapes; headers, footers and page numbers; mail merge; saving and printing. Word processors: Microsoft Word, LibreOffice Writer, Google Docs (any two).

2. Save (Ctrl + S) stores the document under its present name and place; the first time, it asks for a name. Save As (F12 in Word) saves a copy under a new name, in a new place or in another format, keeping the old file as it was.

3. Cut (Ctrl + X) removes the selected text and keeps it on the clipboard to be pasted elsewhere; copy (Ctrl + C) keeps the text in its place and puts a copy on the clipboard. Both are pasted with Ctrl + V.

4. Find (Ctrl + F) searches the document for a word or phrase. Replace (Ctrl + H) finds a word and changes it to another, one at a time or all at once with Replace All — for example changing every "Kathmandu" to "Lalitpur".

5. Font formatting: changing the font type, size, colour and style (bold, italic, underline) of characters. Paragraph formatting: alignment (left, centre, right, justify), line spacing, indentation and space before and after. Bullets and numbering: making lists that start with symbols or numbers. Page layout: margins, orientation (portrait or landscape), page size (A4) and columns.

6. A header is text printed at the top of every page and a footer at the bottom (such as the school name or a date); page numbers number the pages automatically (Insert → Header, Footer, Page Number). A table is inserted with Insert → Table, choosing the number of rows and columns; a picture with Insert → Pictures, choosing the image file, then resizing it by its corner handles.

1. A workbook is a spreadsheet file (such as marks.xlsx); a worksheet is one sheet of rows and columns inside it. A cell is the box where a row and a column meet; its address is column letter plus row number, such as B3. A range is a block of cells, such as A1:D5 (from A1 to D5).

2. A relative reference (such as A2) changes when the formula is copied: copied down one row it becomes A3. An absolute reference (such as $E$1) has dollar signs and stays the same wherever the formula is copied.

3. AutoFill fills a series or copies a formula into neighbouring cells by dragging the fill handle (the small square at the bottom-right corner of the selected cell). Use: typing 1 and 2 and dragging gives 1, 2, 3 … ; typing "Sunday" and dragging gives the days of the week; dragging a formula copies it down a column.

4. (a) =MIN(C2:C30) (b) =COUNT(C2:C30).

5. In B2: =A2*$E$1 (or =A2*$E$1/100 if E1 holds 13 rather than 13%). When the formula is copied down, A2 must change to A3, A4 … for each item, but every row must still use the one VAT rate in E1; the dollar signs keep $E$1 fixed. Without them the copied formulas would point to E2, E3 …, which are empty, giving 0. VAT on Rs 2,500 = 2,500 × 13 ÷ 100 = Rs 325.

6. Column chart — compares values side by side: (c) marks of five students. Bar chart — horizontal bars, good for long category names: (d) population of seven provinces. Line chart — shows change over time: (a) monthly rainfall. Pie chart — shows parts of a whole: (b) share of expenses.

1. Presentation software is application software used to create slides containing text, pictures, charts, audio and video and to show them one by one to an audience. Examples: Microsoft PowerPoint, LibreOffice Impress, Google Slides.

2. A placeholder is a dotted box on a slide that holds a title, text, a picture or a chart ("Click to add title"). A slide layout is the arrangement of placeholders on a slide, such as Title Slide, Title and Content, or Two Content.

3. The slide master (View → Slide Master) is the top slide that stores the design of all slides — background, fonts, colours, logo and placeholder positions. A change made on it appears on every slide at once, which saves time and keeps the slides consistent.

4. Press F5 (or Slide Show → From Beginning) to start from the first slide; press Shift + F5 (or From Current Slide) to start from the slide on screen. Esc ends the show.

5. (1) Open PowerPoint → Blank Presentation, choose a theme on the Design tab. (2) Slide 1 (Title Slide layout): type the school's name and address. (3) Add slides with Home → New Slide: history, facilities (Insert → Pictures, the school photo), results (Insert → Chart, a column chart of pass percentages), and a thank-you slide. (4) Apply a transition from the Transitions tab → Apply To All; save as school.pptx; run with F5.

6. Any four: use one simple theme throughout; keep about six lines of six words per slide (the 6 × 6 rule); use a large, clear font (at least 24 points) with strong contrast between text and background; use pictures and charts instead of long paragraphs; use only a few, gentle animations and transitions; check spelling; end with a summary.

1. A web page is a single document on the World Wide Web, written in HTML and opened in a browser. A website is a collection of related web pages under one domain name, linked together, such as all the pages of neb.gov.np.

2. A URL (Uniform Resource Locator) is the full address of a resource on the web. In https://www.myschool.edu.np/results.html: https is the protocol, www.myschool.edu.np is the domain name (the server), and /results.html is the path to the page on that server.

3. A container (paired) tag has an opening and a closing tag with content between them, such as <b>bold</b> or <p>…</p>. An empty tag has no closing tag and no content, such as <br> (line break) and <img>.

4. An ordered list shows its items with numbers or letters and uses <ol>; an unordered list shows them with bullets and uses <ul>. In both, each item is written in <li>…</li>.

5.

<table border="1">
<tr>
<th>S.N.</th>
<th>Name</th>
<th>Marks</th>
</tr>
<tr>
<td>1</td>
<td>Asha Rai</td>
<td>87</td>
</tr>
<tr>
<td>2</td>
<td>Bikash Thapa</td>
<td>92</td>
</tr>
</table>

<table> makes the table and border="1" draws its lines; <tr> makes each row; <th> makes a bold heading cell and <td> an ordinary cell.

6. Structure: <html> encloses the whole document; <head> holds information about the page, including <title>, the text shown on the browser tab; <body> holds everything shown in the window — headings, paragraphs, lists, pictures, tables. Steps: open a text editor such as Notepad; type the HTML; save it with the extension .html (for example index.html), choosing "All files"; open the file in a browser (double-click it); to change it, edit and save in Notepad, then refresh the browser (F5).

1. The Internet is the worldwide network of networks — the cables, routers and computers joined by TCP/IP. The World Wide Web is one service that runs on the Internet: the collection of linked web pages opened in a browser. E-mail and video calls also use the Internet but are not the Web.

2. To: the main receivers of the message. Cc (carbon copy): others who get a copy; every receiver can see their addresses. Bcc (blind carbon copy): receivers whose addresses are hidden from all the others.

3. Cloud storage keeps files on servers on the Internet instead of on your own device, so they can be opened from any device and are safe if a phone is lost. Examples: Google Drive, Microsoft OneDrive, Dropbox, iCloud.

4. The digital divide is the gap between people who have devices, the Internet and the skills to use them and those who do not — for example, in the 2021 census 45.7% of households in municipalities but only 21.5% in rural municipalities had the Internet. Ways to reduce it: extend cheap broadband and mobile data to rural areas; give schools computers and teach digital skills (also: community information centres, local-language content).

5. E-governance is the use of ICT by the government to give its services and information to people quickly and openly (1 mark). G2C (government to citizen): the Nagarik App, launched in 2021, gives citizens their PAN, driving licence and other records on the phone. G2B (government to business): companies file taxes and register online with government offices. G2G (government to government): offices share records over the government network instead of on paper (3 marks).

6. Advantages: quick and cheap communication across the world; online banking, shopping and learning from home; faster government services. Disadvantages: cyber crime, fraud and loss of privacy; addiction and health problems; the digital divide leaves poorer and rural people behind (any two of each).

1. Computer ethics is the set of moral rules for using computers and the Internet rightly. Any two commandments (Computer Ethics Institute, 1992): do not use a computer to harm other people; do not snoop around in other people's files; do not use a computer to steal; do not copy or use software you have not paid for; do not take other people's work as your own.

2. Phishing is tricking people into giving passwords, OTPs, PINs or card numbers through a fake message, e-mail or website that looks as if it came from a bank, wallet or office. Signs: it creates urgency ("your account will be blocked today"); it asks for an OTP, PIN or password; the sender address or link is slightly wrong; spelling mistakes; a prize you never entered for.

3. Copyright is the legal right of the creator of a work — a book, song, film, photo or program — to control its copying and use; in Nepal it lasts for the author's life plus 50 years. Plagiarism is presenting someone else's words or work as your own without giving credit, such as copying an essay from a website into your project.

4. Cyber bullying is using phones, social media or games to insult, threaten, shame or harass someone again and again. The student should not reply, should save screenshots as evidence, block and report the bully on the platform, and tell a parent or teacher; serious cases can be reported to the Cyber Bureau.

5. Hacking: getting into someone's computer, account or network without permission (an offence under section 45 of the ETA). Identity theft: stealing someone's personal details — name, photo, citizenship number, password — to pretend to be them, open fake accounts or cheat others. Software piracy: copying, selling or using software without a licence. Cyber bullying: harassing or threatening someone repeatedly online.

6. A digital citizen is a person who uses the Internet and digital technology responsibly, safely and with respect for others (1 mark). Any three rules: think before you post — posts stay for ever; keep your accounts private and share no personal details such as address, phone number or school timetable; use strong, different passwords and turn on multi-factor authentication; accept friend requests only from people you know; do not share fake news or others' photos without permission; report abuse (3 marks).

1. Any two: infected pen drives and memory cards; pirated or cracked software and games; e-mail attachments and links from unknown senders; fake websites and apps; files shared over a network.

2. Any four: the computer becomes very slow or hangs; programs crash or the computer restarts by itself; files go missing, change, or cannot be opened; folders on a pen drive turn into shortcuts; unwanted pop-up adverts appear; the antivirus is switched off without your knowing; messages are sent from your account without you.

3. Ransomware is malware that locks (encrypts) a user's files or computer and demands money (a ransom) to unlock them. Example: WannaCry, which on 12 May 2017 locked more than 200,000 computers in over 150 countries and demanded 300 US dollars in Bitcoin.

4. Antivirus software is a utility program that detects, blocks and removes viruses and other malware. Examples: Microsoft Defender, Avast, Kaspersky, Norton, ClamAV (any two).

5. How it works: it compares files with a database of signatures (patterns of known malware) and also watches the behaviour of programs for suspicious actions; its real-time scanner checks every file as it is opened or downloaded; a found threat is cleaned, deleted or put in quarantine; the signature list must be updated regularly (2 marks). Difference: an antivirus checks and cleans the files and programs inside the computer, while a firewall checks the network traffic coming in and going out and blocks unauthorised connections; the two work together (2 marks).

6. Any four: install an antivirus and keep it updated; turn on automatic updates for the operating system and apps; scan pen drives before opening them; download software only from official sites, never cracked copies; do not open attachments or links from unknown senders; keep backups by the 3-2-1 rule (three copies, two kinds of media, one kept elsewhere); use strong passwords with multi-factor authentication.

1. A hub copies every signal it receives to all its ports, so all computers share the speed and data can collide. A switch reads the MAC address and sends each frame only to the port of the destination computer, so it is faster and more private.

2. A LAN (Local Area Network) covers a small area such as a room, building or school campus and is fast — for example a school computer lab. A WAN (Wide Area Network) covers a country or the whole world and joins many LANs — for example the Internet, or the network joining a bank's branches across Nepal.

3. Wired: twisted-pair (UTP) cable, coaxial cable, optical fibre (any two). Wireless: radio waves (Wi-Fi), Bluetooth, microwave, satellite, infrared (any two).

4. 120 MB = 120 × 8 = 960 megabits. Time = 960 ÷ 16 = 60 seconds (1 minute).

5. 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 (1 mark). Any three components: server — a powerful computer that provides services such as files, printing or websites to others; client — a computer that uses those services; NIC — the network card that connects a device to the network and carries its MAC address; switch — the central device that sends data only to its destination; router — joins different networks, such as the school LAN and the Internet, using IP addresses; modem — converts digital signals for the telephone or cable line and back (3 marks).

6. (1) The Internet is not one network: it is millions of LANs and WANs of homes, schools, companies and countries joined together by routers. (2) ISPs (Internet Service Providers) such as Nepal Telecom and WorldLink connect users to the Internet, and ISPs exchange traffic with each other (in Nepal at npIX) and with other countries. (3) Data is broken into small packets, each carrying the sender's and receiver's IP addresses, which may travel by different routes and are joined again at the destination. (4) All these different networks can work together because they follow the same rules, TCP/IP: IP addresses and routes the packets, TCP checks that every packet arrives and puts them in order.

1. 1\times2^5 + 0\times2^4 + 1\times2^3 + 1\times2^2 + 0\times2^1 + 1\times2^0 = 32 + 0 + 8 + 4 + 0 + 1 = 45, so (101101)_2 = (45)_{10}.

2. 3\times8^2 + 4\times8^1 + 6\times8^0 = 192 + 32 + 6 = 230, so (346)_8 = (230)_{10}.

3. Octal: groups of three from the right: 001 110 101 101 → 1, 6, 5, 5, so (1655)_8. Hexadecimal: groups of four from the right: 0011 1010 1101 → 3, A, D, so (3AD)_{16}. (Both equal 941 in decimal.)

4. 1 GB = 1024 MB, so 2 GB = 2 × 1024 = 2048 MB; 1 MB = 1024 KB, so 2048 × 1024 = 2,097,152 KB.

5. Each hexadecimal digit becomes four bits: 3 = 0011, A = 1010, F = 1111, so (3AF)_{16} = (1110101111)_2. Regroup in threes from the right: 001 110 101 111 → 1, 6, 5, 7, so (3AF)_{16} = (1657)_8. Check: 3\times256 + 10\times16 + 15 = 768 + 160 + 15 = 943, and 1\times512 + 6\times64 + 5\times8 + 7 = 512 + 384 + 40 + 7 = 943 ✓.

6. (a) Each octal digit becomes three bits: 7 = 111, 2 = 010, 5 = 101, giving 111010101. Regroup in fours from the right: 0001 1101 0101 → 1, D, 5, so (725)_8 = (1D5)_{16} (both are 469 in decimal). (b) 219 ÷ 2 = 109 r 1; 109 ÷ 2 = 54 r 1; 54 ÷ 2 = 27 r 0; 27 ÷ 2 = 13 r 1; 13 ÷ 2 = 6 r 1; 6 ÷ 2 = 3 r 0; 3 ÷ 2 = 1 r 1; 1 ÷ 2 = 0 r 1. Reading upwards, (219)_{10} = (11011011)_2. Check: 128 + 64 + 16 + 8 + 2 + 1 = 219 ✓.

1. A pixel (picture element) is the smallest dot of a raster image or screen; it shows one colour. Resolution is the number of pixels in an image or screen, written as width × height, such as 1920 × 1080; more pixels show more detail.

2. Pixels = 800 × 600 = 480,000; 24 bits = 3 bytes per pixel, so size = 480,000 × 3 = 1,440,000 bytes; ÷ 1024 = 1,406.25 KB (about 1.37 MB).

3. JPEG uses lossy compression: it throws away fine detail to make photographs very small, and it has no transparency. PNG uses lossless compression, keeps every pixel exactly, supports transparent backgrounds, and suits logos, screenshots and diagrams.

4. GIMP (GNU Image Manipulation Program) is a free raster editor for photographs and paintings, working pixel by pixel with layers. Inkscape is a free vector editor for logos, posters and diagrams that stay sharp at any size; it saves SVG files.

5. BMP — Bitmap: uncompressed, so files are very large. JPEG — Joint Photographic Experts Group: lossy, small files for photographs. PNG — Portable Network Graphics: lossless, supports transparency. GIF — Graphics Interchange Format: only 256 colours, supports simple animation. SVG — Scalable Vector Graphics: vector format, sharp at any size, used on websites.

6. (1) Open Paint and set the page size with Resize (or Image Properties). (2) Use the Fill tool to colour the background, and the shapes tool (rectangle, star) with Colour 1 and Colour 2 for a border and decorations. (3) Use the Text tool (A) to type "Happy Dashain" and a short wish, choosing font, size and colour; draw a kite or a jamara with the brush or pencil. (4) File → Save As → PNG picture, type a name such as dashain.png and click Save.

1. Linear multimedia plays from beginning to end in a fixed order, and the user only watches, like a film or a TV advertisement. Interactive multimedia lets the user control it — click, choose, answer — like a game, a website or the E-Paath lessons.

2. Video is recorded from real life with a camera. Animation is made of drawn or computer-made pictures shown quickly, usually 12 to 30 a second, so that they seem to move.

3. Input: microphone, webcam, digital camera, scanner, graphics tablet (any two). Output: monitor, speakers, headphones, projector (any two).

4. Any two: medical images such as X-ray, CT and MRI scans; telemedicine — video consultations with distant doctors; training doctors and nurses with videos and 3D models; health awareness campaigns with videos and animations.

5. Education: interactive lessons (E-Paath), videos and animations, projectors in classrooms and online classes make learning interesting and easier to understand. Entertainment: films, music, video games, YouTube and virtual reality. Business: advertisements, product videos on shopping sites such as Daraz, presentations and tourism videos (one or two explained points for each; health or communication may replace one).

6. Advantages: it holds attention and makes learning interesting; it explains hard ideas with pictures, sound and motion; it suits learners who learn by seeing, hearing or doing; it can reach a large audience. Disadvantages: making it takes time, skill and costly equipment; its large files need storage and fast Internet; too many effects can distract (any two of each, 2 marks). Size: 44,100 × 16 × 2 × 60 ÷ 8 = 10,584,000 bytes, about 10.1 MB (2 marks).

1. Any two: finiteness — it ends after a limited number of steps; definiteness — every step is clear and has only one meaning; input and output — it states what it receives and produces at least one result; effectiveness — every step can actually be carried out.

2. An algorithm is written in words as numbered steps, while a flowchart is drawn with standard symbols joined by arrows. An algorithm is quicker to write and change; a flowchart makes branches and loops easier to see.

3. Step 1: Start. Step 2: Read A, B, C and D. Step 3: SUM = A + B + C + D. Step 4: AVG = SUM ÷ 4. Step 5: Display AVG. Step 6: Stop.

4. Pseudocode is an algorithm written in short, structured English statements with keywords such as INPUT, PRINT, IF … ENDIF and WHILE … ENDWHILE; it looks like a program but cannot be run. Example: BEGIN / INPUT A, B / SET S = A + B / PRINT S / END.

5. Algorithm. Step 1: Start. Step 2: Set S = 0 and I = 2. Step 3: Is I ≤ 50? If no, go to step 6. Step 4: S = S + I. Step 5: I = I + 2, and go to step 3. Step 6: Display S. Step 7: Stop. Flowchart. Start → rectangle "S = 0, I = 2" → diamond "Is I ≤ 50?" → Yes: rectangle "S = S + I" → rectangle "I = I + 2" → arrow back to just above the diamond; No: parallelogram "Display S" → Stop. The output is 650, which a QBASIC version of this algorithm also printed.

6. (1) Problem analysis: understand the problem and list its input, process and output. (2) Program design: plan the steps with an algorithm, flowchart or pseudocode. (3) Coding: write the program in a language such as QBASIC. (4) Testing and debugging: run it with test data and remove errors. (5) Documentation: write comments and a user guide. (6) Implementation and maintenance: install it, then fix and update it when needed.

1. Machine language is written in binary (0s and 1s), is understood directly by the processor and needs no translator. Assembly language uses short words called mnemonics, such as MOV and ADD, and needs an assembler to translate it into machine code. Both are low-level and machine-dependent.

2. A syntax error breaks the grammar rules of the language, so the program does not run, for example PRNT for PRINT. A logical error is a mistake in the method, so the program runs but the output is wrong, for example A = L + B for the area of a rectangle.

3. Valid: SUM, NAME$, AVG.MARKS. Invalid: 3RD — it begins with a digit; ROLL NO — it contains a space; END — it is a keyword.

4. INTEGER (%), LONG (&), SINGLE (!, the default), DOUBLE (#) and STRING ($).

5. Features (any three): English-like words and mathematical signs; easy to write, read and correct; portable (machine-independent); must be translated by a compiler or interpreter; one statement does the work of many machine instructions (2 marks). Languages (2 marks): BASIC — John Kemeny and Thomas Kurtz (1964), whose QBASIC version came from Microsoft (1991); Python — Guido van Rossum (1991); C — Dennis Ritchie (1972); Java — James Gosling (1995).

6. Line 2: INPUT "Enter the radius" R needs a semicolon or comma after the prompt — a syntax error (FreeBASIC reported "Expected ',' or ';'" here). Line 3: R * 2 should be R ^ 2 — a logical error, since the area is πr². Line 6: PRNT — a syntax error. Correct program:

CLS
REM Area and circumference of a circle
INPUT "Enter the radius"; R
A = 22 / 7 * R ^ 2
C = 2 * 22 / 7 * R
PRINT "Area ="; A
PRINT "Circumference ="; C
END

Enter the radius? 7
Area = 154
Circumference = 44

With the logical error left in, the same input printed "Area = 44", which only a check against the formula reveals.

1. 8, COM, PUT, ER — one on each line (the 8 has a space in front because it is a number).

2. A = 1 / 2 * B * H; I = P * T * R / 100; C = SQR(A ^ 2 + B ^ 2).

3.

CLS
REM Days into years, months and days
INPUT "Number of days"; D
Y = D \ 365
R = D MOD 365
M = R \ 30
DY = R MOD 30
PRINT Y; "years"; M; "months"; DY; "days"
END

Number of days? 800
 2 years 2 months 10 days

Check: 2 × 365 + 2 × 30 + 10 = 730 + 60 + 10 = 800 ✓.

4. A doubles on every pass: 4, 8, 16, 32. Output: 4 8 16 32.

5.

CLS
REM The first 10 odd numbers and their sum
S = 0
FOR I = 1 TO 19 STEP 2
    PRINT I;
    S = S + I
NEXT I
PRINT
PRINT "Sum ="; S
END

 1  3  5  7  9  11  13  15  17  19
Sum = 100

6.

CLS
REM NEPAL pattern with LEFT$
W$ = "NEPAL"
FOR I = 1 TO LEN(W$)
    PRINT LEFT$(W$, I)
NEXT I
END

N
NE
NEP
NEPA
NEPAL

7.

CLS
REM Electricity bill
INPUT "Units used"; U
IF U <= 100 THEN
    B = U * 8
ELSE
    B = 100 * 8 + (U - 100) * 11
END IF
IF B < 100 THEN B = 100
PRINT "Bill = Rs"; B
END

Two runs:

Units used? 150
Bill = Rs 1350

Units used? 10
Bill = Rs 100

Check: 100 × 8 + 50 × 11 = 800 + 550 = 1,350 ✓; 10 units cost Rs 80, which is raised to the minimum Rs 100.