NEB 2079 Grade 12 Computer Exam Paper Solution

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Group 'A'

Rewrite the correct options of each question in your answer sheet.

1. Which of the following SQL statement is used to DELETE rows from a database table?

A) DELETE

B) REMOVE

C) DROP

D) CLEAR

Ans: Option C: Drop  

2. A field that is used to uniquely define a particular record in a table is called:

A) Primary Key

B) Entity

C) Relationship

D) Constraints

Ans: Option A: Primary Key

3. What does "MAC" stands for in MAC Address?

A) Mandatory Access Control

B) Media Access Control

C) Micro Access Control

D) Media Access Certificate

Ans: Option B: Media Access Control

4. What is the correct syntax for referring to an external JavaScript script?

A) <script src="myscript.js"></script>

B) <script href="myscript.js"></script>

C) <js href="myscript.js"></js>

D) <js src="myscript.js"></js>

Ans: Option A: <script src="myscript.js"></script>

5. Which of the following is the correct way of defining a variable in PHP?

A) $variable name = value;

B) $variable_name = value;

C) $variable_name = value

D) $variable name as value;

Ans: Option B: $variable_name = value;

6. What is the output of C program?

void main(){ int b=25;

//b memory location=1234;

int *p; p=&b; printf("%d %d", &b, p);}

A) 25 25

B) 1234 1234

C) 25      1234

D) 1234                 25

Ans: Option B:  1234       1234

7. Which feature of OOP is illustrated the code reusability?

A) Polymorphism

B) Abstraction

C) Encapsulation

D) Inheritance

Ans: Option D: Inheritance

8. Which of following is the discovering requirement from a user in the requirement collection process?

A) Feasibility study

B) Requirement Elicitation

C) Requirement Specification

D) Requirement validation

Ans: Option B: Requirement Elicitation

9. What devices are detecting and responding to changes in an environment that are embedded in smart phones and an integral part of the Internet of Things (IoT)?

A) Wi-Fi

B) Barcode

C) RFID

D) Sensors

Ans: Option D: Sensors

Group 'B'

Short answer questions

10. Differentiate the centralized and distributed database system.

Ans:

Centralized and Distributed Database Systems are two different approaches for managing data in a database. Here are the differences between the two:

Basis of Comparison	Centralized	Distributed
Location	It is managed by a single machine or system which is at a single location	It is spread and split up across various storage device locations
Maintenance	Easy to maintain	Difficult to maintain
Efficiency	Less Efficient	More Efficient
Failure	Entire data gets lost	Still able to access other databases
Response Speed	Slow	Fast
Communication Cost	High	Low

OR

What are the purposes of normalization? Give an example of 2NF.

Purpose of Normalization are:

a.       Normalization Process helps to produce cost-effective database systems

b.       Normalization eliminates redundant (repetitive) data

c.       Normalization reduces the amount of storage needed to store the data

d.       Normalization ensures that the data duplication is minimized.

e.       Normalization avoids unnecessary data conflicts

f.        Normalization improves the database performance

g.       Normalization helps for faster searching of data

Example of 2NF:

In 2NF, a table must first meet the requirements of 1NF, and all non-key attributes must depend on the entire primary key, not just part of it.

To illustrate, consider a hypothetical table of customers and their orders:

Customer ID	Order ID	Product Name	Quantity
001	001	iPhone	2
001	002	MacBook Pro	1
002	003	iPad	1
002	004	iMac	1

In this table, the primary key is a combination of Customer ID and Order ID. However, the Product Name attribute is dependent on only the Order ID and not on the entire primary key. To normalize this table to 2NF, we need to separate it into two tables:

Table 1: Orders

Order ID	Customer ID
001	001
002	001
003	002
004	002

Table 2: Order Details

Order ID	Product Name	Quantity
001	iPhone	2
002	MacBook Pro	1
003	iPad	1
004	iMac	1

Now, the Product Name attribute is fully dependent on the entire primary key of the Order Details table, which satisfies the requirements of 2NF.

 

11. Write a program to find the factorial of any given number using JavaScript.

Ans:

function factorial(num) {

  if (num === 0) {

    return 1;

  } else {

    return num * factorial(num - 1);

  }

}

const inputNum = prompt("Enter a number to find its factorial:");

const num = parseInt(inputNum);

if (isNaN(num)) {

  console.log("Invalid input. Please enter a valid number.");

} else {

  const result = factorial(num);

  console.log(`The factorial of ${num} is: ${result}`);

}

OR

How do you fetch data from database in PHP and display it in form? Describe.

Ans:

<html>

<title>Displaying queries in tables</title>

<body>

Displaying queries in tables <br>

<?php

$servername = "localhost";

$username = "root";

$password = "";

$dbname = "db_bca";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error)

{

die("Connection failed: " . $conn->connect_error);

}

$sql = "SELECT * FROM student";

if($result = mysqli_query($conn, $sql)){

if(mysqli_num_rows($result) > 0){

echo "<table border=1>";

echo "<tr>";

echo "<th>RollNo</th>";

echo "<th>Name</th>";

echo "<th>Class</th>";

echo "<th>Marks</th>";

echo "<th>PhoneNo</th>";

echo "</tr>";

while($row = mysqli_fetch_array($result)){

echo "<tr>";

echo "<td>" . $row['RollNo'] . "</td>";

echo "<td>" . $row['Name'] . "</td>";

echo "<td>" . $row['Class'] . "</td>";

echo "<td>" . $row['Marks'] . "</td>";

echo "<td>" . $row['PhoneNo'] . "</td>";

echo "</tr>";

}

echo "</table>";

// Free result set

mysqli_free_result($result);

} else{

echo "No records matching your query were found.";

}

} else{

echo "ERROR: Could not able to execute $sql. " . mysqli_error($conn);

}

?>

</body>

</html>

12. Compare the OOPs and procedural programming language.

Ans:

Basic Comparison Between OOP and POP is:

Feature	Object-Oriented Programming (OOP)	Procedural Programming
Basic Programming	Objects and classes	Functions and procedures
Programming Paradigm	Object-Oriented Programming Paradigm	Imperative Programming Paradigm
Data Abstraction	Encapsulation, Inheritance, Polymorphism	Structured programming
Program Structure	Program divided into Objects	Program divided into Functions
Data Handling	Object State	Global variables
Data Access	Methods or Functions	Function parameters
Code Reusability	Highly reusable	Reusability is difficult
Memory Management	Automatic garbage collection	Manual memory management
Error Handling	Exception handling	Error codes and returns

 

13 What are the major activities performed to design the software? Describe.

Ans:

The major activities performed to design software are:

1. Requirements analysis: Gathering and documenting requirements from stakeholders.
2. Design: Creating a design solution that meets the requirements, including architecture, data model, algorithms, and user interface.
3. Implementation: Writing and testing code based on the design.
4. Testing: Evaluating the software to ensure it meets the requirements and is free of defects.
5. Deployment: Releasing the software to the end-users or customers.
6. Maintenance: Fixing bugs, adding new features, and updating the software to meet changing requirements or environment.

14. Explain the popular five-application areas of AI.

Ans:

AI (Artificial Intelligence) has found its application in various fields. Here are five popular application areas of AI:

1. Natural Language Processing (NLP): AI that helps computers understand and use human language, used in chatbots, virtual assistants, and sentiment analysis.
2. Computer Vision: AI that enables computers to interpret and understand visual information, used in image and video recognition, facial recognition, object detection, and self-driving cars.
3. Robotics: AI used in robots to improve their behavior and decision-making abilities, used in manufacturing, healthcare, and other industries.
4. Predictive Analytics: AI algorithms used to analyze data and predict future outcomes, used in finance, healthcare, and marketing.
5. Gaming: AI used to create intelligent non-player characters (NPCs) that respond to the player's actions and generate procedurally generated content to make games more varied and exciting.

Group 'C'

Long answer questions

15. Compare the star and ring topology with pros and cons. Which of date communication cable is more appropriate to design the local area network? Describe.

Ans:

Star and ring topologies are two common network topologies used in Local Area Networks (LANs). Here are some pros and cons of each topology:

Star Topology:

Pros	Cons
Easy to install and manage.	Single point of failure in the central hub or switch, which can bring down the entire network.
Fault-tolerant as each device is connected to a central hub or switch, so failure of one device does not affect the entire network.	High cost as it requires additional equipment like hubs or switches.
Scalable as new devices can be added to the network easily.	Performance may be impacted by the capacity of the central hub or switch.

Ring Topology:

Pros	Cons
Efficient as data flows in a circular pattern with each device transmitting and receiving data.	Difficult to install and manage as it requires precise configuration and maintenance.
No collisions as only one device can transmit data at a time, which reduces packet loss.	Failure of one device can affect the entire network as data flows through each device.
Cost-effective as it requires less cabling than a star topology.	Not easily scalable as adding new devices requires changes to the entire network.

Second Part:

The most commonly used cables for LAN are twisted pair cable, coaxial cable, and fiber optic cable. Among them, the most used one is Fiber optic cable due to its speed and reliability.

Fiber optic cable is the fastest and most expensive type of LAN cable. It uses glass or plastic fibers to transmit data signals using light. Fiber optic cable can transmit data over very long distances at very high speeds and is often used in wide area networks (WANs). However, it is not commonly used in small to medium-sized LANs due to its high cost.

16. What is structure? Write a program to input roll, name, and age of 5 students and display them properly using structure.

Ans:

Structure is one which is used to store related fields of different data types. Simply structure is

one that can store heterogeneous data.

Program:

#include <stdio.h>

#include <string.h> 

// Define a structure to store student details

struct Student {

   int roll;

   char name[50];

   int age;

}; 

int main() {

   // Declare an array of 5 Student structures

   struct Student students[5];

 

   // Input details for each student

   for (int i = 0; i < 5; i++) {

      printf("Enter details for student %d:\n", i+1);

      printf("Roll: ");

      scanf("%d", &students[i].roll);

      printf("Name: ");

      scanf("%s", students[i].name);

      printf("Age: ");

      scanf("%d", &students[i].age);

      printf("\n");

   } 

   // Display the details of all students

   printf("Details of all students:\n");

   for (int i = 0; i < 5; i++) {

      printf("Roll: %d\n", students[i].roll);

      printf("Name: %s\n", students[i].name);

      printf("Age: %d\n\n", students[i].age);

   } 

   return 0;

}

OR

Write a C program to enter ID, employee name, and post of the employee and store them in a data file named "emp.txt". Display each record on the screen in an appropriate format.

Ans:

#include <stdio.h> 

struct Employee 

{

    int id;

    char name[50];

    char post[50];

}; 

int main() {

    struct Employee emp;

    FILE *fp;

    fp = fopen("emp.txt", "a");  // open file in append mode

 

    // Input employee details

    printf("Enter employee ID: ");

    scanf("%d", &emp.id);

    printf("Enter employee name: ");

    scanf("%s", emp.name);

    printf("Enter employee post: ");

    scanf("%s", emp.post);

 

    // Write employee details to file

    fprintf(fp, "%d %s %s\n", emp.id, emp.name, emp.post);

    fclose(fp);  // close file

 

    // Display employee details from file

    fp = fopen("emp.txt", "r");  // open file in read mode

    printf("\nEmployee Details:\n");

    while (fscanf(fp, "%d %s %s", &emp.id, emp.name, emp.post) != EOF) {

        printf("ID: %d\n", emp.id);

        printf("Name: %s\n", emp.name);

        printf("Post: %s\n\n", emp.post);

    }

    fclose(fp);  // close file 

    return 0;

}