NEB Class 12 Science Computer Science Question Paper 2081 Nepal

Standard SQL syntax to select all columns is SELECT * FROM enp WHERE eopid = 103;

A distributed database system stores data across multiple geographically dispersed sites, allowing data to be located closer to users and improving performance.

Private IPv4 ranges are 10.0.0.0/8 (10.10.10.10), 172.16.0.0/12 (172.16.10.1) and 192.168.0.0/16 (192.168.1.1). 203.0.113.10 lies outside these private ranges, so it is a public address.

A JavaScript for loop requires initialization, condition and increment separated by semicolons: for (var i = 0; i < 5; i++) {}.

mysqli_query() executes a query on a connection opened with the mysqli extension.

A structure in C is declared with the struct keyword followed by a tag name and a brace-enclosed member list: struct <name> { }.

The address-of operator & returns the memory address of a variable.

Inheritance lets a class (subclass) acquire the properties and behavior of another class (superclass).

The Waterfall model follows a strictly linear, sequential progression of phases from requirements gathering through to maintenance.

Advantages of DBMS over file-based systems:

• Reduced data redundancy and inconsistency: A DBMS stores data in a centralized, normalized way, minimizing duplicate copies that plague separate flat files.
• Data integrity and constraints: Rules (primary keys, foreign keys, validation) enforce correctness automatically.
• Data security and access control: Users get role-based privileges; file systems offer only crude file-level protection.
• Concurrent multi-user access: Locking and transactions (ACID) allow many users to work safely at once.
• Data independence: Applications are insulated from changes in physical/logical storage.
• Backup, recovery and query power: Built-in recovery from failures and a powerful query language (SQL) for ad-hoc retrieval, versus custom programs needed for files.

OR — 2NF vs 1NF:

• A relation is in 1NF if all attribute values are atomic (no repeating groups or multivalued attributes).
• A relation is in 2NF if it is in 1NF and every non-prime attribute is fully functionally dependent on the whole primary key (i.e., no partial dependency on part of a composite key).
• Benefits of 2NF: removes partial-dependency redundancy, reduces update/insertion/deletion anomalies, saves storage, and keeps data more consistent.

JavaScript even/odd function:

function checkEvenOdd(num) {
  if (num % 2 === 0) {
    console.log(num + " is Even");
  } else {
    console.log(num + " is Odd");
  }
}

checkEvenOdd(7); // Output: 7 is Odd
checkEvenOdd(10); // Output: 10 is Even

The function uses the modulus operator %: if num % 2 equals 0 the number is even, otherwise odd.

OR — mysqli_connect():

mysqli_connect() opens a new connection from a PHP script to a MySQL database server. It returns a connection (link) object on success or false on failure.

Usage:

$conn = mysqli_connect("localhost", "root", "password", "mydb");

Parameters:

• host – server name or IP (e.g. "localhost").
• username – MySQL user name.
• password – password for that user.
• database – (optional) the default database to use.
• (optional port and socket).

Class: A class is a user-defined blueprint or template that defines the attributes (data members) and behaviors (methods) common to a group of objects. It does not occupy memory by itself.

Object: An object is a concrete instance of a class. It is created from the class blueprint and occupies memory, holding actual values for the attributes.

Real-world example: Consider a class Car with attributes color, brand, speed and methods start(), accelerate(), brake(). A specific car such as a red Toyota running at 60 km/h is an object of the Car class. From the single Car blueprint we can create many objects (a red Toyota, a blue Honda, etc.), each with its own data.

During the analysis phase of the SDLC, requirement gathering (elicitation) techniques are used to capture exactly what users need so the system is built correctly. Key techniques and how they help:

• Interviews: Direct one-to-one questioning of stakeholders reveals detailed needs, expectations and constraints.
• Questionnaires/Surveys: Collect requirements quickly from a large number of users and quantify common needs.
• Observation: Watching users perform their actual work uncovers tacit needs and real workflows they may not articulate.
• Document analysis: Studying existing forms, reports and procedures shows current data and rules the new system must support.
• Brainstorming/JAD sessions: Group discussions generate and reconcile requirements among many stakeholders.
• Prototyping: Early models let users react to a tangible version, clarifying and refining ambiguous requirements.

Together these techniques reduce ambiguity, expose conflicting requirements early, ensure completeness, and give analysts an accurate, validated grasp of user needs—minimizing costly changes later in development.

Five examples of AI applications in education:

1. Intelligent Tutoring Systems – software that adapts lessons and provides personalized one-to-one style guidance to each student.
2. Automated grading/assessment – AI grades objective tests, quizzes and even essays, giving instant feedback.
3. Personalized/adaptive learning platforms – systems that adjust content and pace to each learner's strengths and weaknesses.
4. Chatbots and virtual assistants – answer student queries about courses, admissions and study material 24/7.
5. Plagiarism detection – AI compares submissions against large databases to detect copied content.

(Other valid examples: AI-based proctoring of online exams, learning analytics to predict at-risk students, language-learning apps with speech recognition.)

Star Topology

• Architectural layout: Every node connects by its own dedicated cable to a central device (hub or switch). The central device is the focal point of all connections.
• Data transmission: A node sends data to the central hub/switch, which then forwards it to the destination node. A switch forwards only to the intended port, allowing simultaneous communications.
• Reliability: Failure of one cable/node affects only that node; the rest of the network keeps working. However, failure of the central device disables the whole network.
• Performance/scaling: Adding a node only needs another link to the hub; performance stays high (especially with a switch). Easy to manage and troubleshoot. Needs more cabling.

Bus Topology

• Architectural layout: All nodes share a single common backbone cable (the bus), tapping into it along its length, terminated at both ends.
• Data transmission: A transmitting node broadcasts the signal along the whole bus; every node receives it but only the addressed node accepts it. Only one node can transmit at a time, so a method like CSMA/CD handles collisions.
• Reliability: A break or fault in the backbone brings down the entire network; faults are hard to isolate.
• Performance/scaling: Uses the least cable and is cheap for small networks, but performance degrades sharply as more nodes are added because of collisions and shared bandwidth.

Key differences (summary)

In modern computing environments the star topology dominates (Ethernet with switches, Wi-Fi access points) because of its reliability, easy fault isolation and support for simultaneous high-speed transmission, whereas the bus topology is largely obsolete.

C program using a structure for five books:

#include <stdio.h>

struct Book {
    char title[50];
    char author[50];
    char publisher[50];
    float price;
};

int main() {
    struct Book books[5];
    int i;

    // Input details of five books
    for (i = 0; i < 5; i++) {
        printf("Enter title, author, publisher and price of book %d:\n", i + 1);
        scanf("%s %s %s %f", books[i].title, books[i].author,
              books[i].publisher, &books[i].price);
    }

    // Print details of five books
    printf("\nDetails of Books:\n");
    for (i = 0; i < 5; i++) {
        printf("Book %d: %s, %s, %s, Rs. %.2f\n", i + 1,
               books[i].title, books[i].author,
               books[i].publisher, books[i].price);
    }

    return 0;
}

Here struct Book groups four related fields; an array of five Book structures stores all records, which are then printed in a loop.

OR — Binary file handling in C:

A binary file stores data in the same internal (binary) representation used in memory, rather than as human-readable text. Binary files are opened in binary mode (e.g. "rb", "wb", "ab") and are faster and more compact for numeric data, with no formatting conversion.

• putw(int w, FILE *fp) writes an integer w to the file fp in binary form. It returns the value written (or EOF on error).
• getw(FILE *fp) reads the next integer from the binary file fp. It returns the integer read, or EOF at end of file/on error.

Example:

#include <stdio.h>

int main() {
    FILE *fp;
    int n, i;

    // Write integers to a binary file
    fp = fopen("numbers.dat", "wb");
    for (i = 1; i <= 5; i++)
        putw(i * 10, fp);   // writes 10,20,30,40,50
    fclose(fp);

    // Read them back
    fp = fopen("numbers.dat", "rb");
    while ((n = getw(fp)) != EOF)
        printf("%d ", n);   // prints 10 20 30 40 50
    fclose(fp);

    return 0;
}

Thus putw() and getw() provide simple integer-level binary I/O, complementing fread()/fwrite() for block I/O.