HISSAN computer science || Grade 12 Computer Science 2081 – Full Questions & Solutions

 

 

HISSAN CENTRAL EXAMINATION 2081 (2025)

Grade: XII Time: 2 hrs

F.M.: 50

COMPUTER SCIENCE (4281 M1)

Candidates are required to give their answers in their own words as far as practicable.

Multiple Choice Questions.

GROUP A

Writes the best alternative.

[9×1=9]

1.Which database language is used for defining schema structures?

a)DML                                                b)DDL

c)DCL                                                d)TCL

 

ans: b)DDL

 

2. Which of the following operations are used to extract data from a
database?

a)SELECT                                         b)DELETE

c)UPDATE                                         d)INSERT

 

ans: a)SELECT

3. Which of the following is NOT a valid PHP data type?

a)String                              b)Float

c)Character                      d)Boolean

 

ans: c)Character

4.Which symbol is used for single-line comments in JavaScript?

a)//                                      b)/* */

c)<!-- -->                            d)**

 

ans a)//

5.What is the default return type of a function in C if no return type is
specified?

a)void                                 b)int

c)char                                 d)float

 

Ans: b)int

6. Which network device is used to connect multiple networks together?

a)Hub                                                b)Switch

c)Router                                            d)Repeater

 

ans: c)Router

7. What is cloud computing?

a)A type of software                                                                                 b)A type of hardware

c)The delivery of computing services over the internet                d)A programming language

 

Ans: c)The delivery of computing services over the internet             

8. Which of the following is NOT a principle of OOP?

a)Encapsulation                            b)Inheritance

c) Compilation                                d)Polymorphism

 

Ans: c) Compilation

9.Which of the following SDLC models is also known as the "linear-
sequential model"?

a)Spiral Model                                b)Waterfall Model

c)Agile Model                                  d)V-Model

 

Ans: b)Waterfall Model

Short Answer Questions: 15×5-25]
GROUP B

10. What is database? Explain any three advantages of DBMS.                                             [2+3=5]

Ans:-

Database:-

It is a collection of interrelated data . These can be stored in the form of tables. A database can be of any size and varying complexity. A database may be generated and manipulated manually or it may be computerized. 

Example: 

Customer database consists the fields as cname, cno, and ccity.

DBMS:

The software tool package that helps gatekeeper and manage data storage, access and maintenances. It can be either in personal usage scope (MS Access, SQLite) or enterprise level scope (Oracle, MySQL, MS SQL, etc). 

DBMS advantages:-

1. Multiple users: 

DBMS allows us to share the data among many users and from different sites. It is done to enter multiple data and for the customers. For a complex database, we assign limited access control for them.

2. Backup: 

Backup means storing the data in different location or machines. It is done by users or the computers themselves to recover the data in the case of failure. Like reserving a ticket online, suppose 100 persons have reserved and the suddenly the system became down, Now what to do in this scenario, we need old data and new data both. Hence the administrator recovers the data from backup.

3.Data security:-

 Obviously, the data for an organization is crucial. What would happen if a hacker or unauthorized person uses it? Our data could be public and  misused by third persons for their own purpose. To avoid  that risk  we assign specific roles to users. We may filter incoming and outgoing data. For this the DBMS is helpful.

OR

Explain second normal form with example.                                                                                  [5]

Ans:-

Second normal form:-

A table is said to be in 2N if it satisfies the following conditions.

1. If it is in 1N.

2.If all non-key attributes are fully functionally dependent on entire primary key, not on only its part.

Example:

Let us consider the following table.

item	colors	price	tax
T-shirt	Red	13	0.45
T-shirt	Blue	13	0.45
polo	red	12	0.4

Here, the table is already in 1N. But it is not in 2N because non-key attributes price and tax depend on item not on colors which is a part of primary key(items, colors). This violates the rule for 2N as it says the non-key attribute is functionally depend on primary key fully, not partially.

To convert this into 2N, we are going to break this into two tables as given here.

items

item	colors
T-shirt	Red
T-shirt	Blue
polo	red

and

Tax

item	price	tax
T-shirt	13	0.45
T-shirt	13	0.45
polo	12	0.4

Now it is in 2NF.

11. Write a javascript function that takes two numbers as arguments and returns their sum.[5]

Ans:

<script>
                var a,b;
                function sum(a,b)
                {
            return a+b;
                }
                a=parseInt(prompt("enter a number for a"));
                b=parseInt(prompt("enter a number foor b"));
                document.write(sum(a,b));
        </script>

OR
Write a PHP script to find the largest of three numbers.

Ans:-

<?php
            $number1 = 10;
            $number2 = 25;
            $number3 = 15;
            if ($number1 >= $number2 && $number1 >= $number3) 
            {
                $greatest = $number1;
            } 
            elseif ($number2 >= $number1 && $number2 >= $number3)
             {
                $greatest = $number2;
            } 
            else 
            {
                $greatest = $number3;
                }
        echo "The greatest number is: " . $greatest;
?>

12. Explain the concept of inheritance in OOP. How does inheritance help in code reusability?[2+3]

Ans:-

Inheritance:-

                   It is the fundamental concept in OOP programming paradigm. As the name says, we derive some new classes from existing classes. The class we derive from is called main class or super class where as the derived class is called child class or sub class. This derivation helps us to use the properties and methods of parent class by child class. This feature helps us to use the code of parent class by child class without re-writing the code.

second part:

This feature helps us in code re-usability  in following way.

1.Reusing the code: Since  inheritance allows us to use the property and method of suer class, we do not need to write them again and again. So it saves our time. Example: multiple vehicle types(car and truck) share common property from class vehicle.

2.Extensibility: Subclasses can extend the super class by adding new property and methods. Not only that much,  we can add new classes as per demand without modifying existing ones.

3.Easier maintenance: Changes in the parent classes automatically apply to all child classes, making  update easier and consistent.

13 What is e-learning? Write any three advantages of e-learning.                                        [2+3]

Ans:-

e-learning:-

E-LEARNING is a flexible term used to describe a means of teaching through technology such as a network, browser, CDROM or DVD multimedia platforms. In today's world, mostly, we use internet to learn or teach or share the contents. We do not need to be in a fixed location  to learn. It is just like learn 'wherever you go'

Advantages:

1. Availability of same course to millions. 

2. Boon for Working class. 

3. Apprehensive Employers. 

14. What is the purpose of the requirements gathering phase in the SDLC? Explain. [2+3]

 Ans:-

The primary purpose of requirement gathering in SDLC is to accumulate, analyze and document requirements and assumptions of clients/stakeholders for whom possibly system is being developed. In this phase the development team becomes very clear about what is to be provided from the client side, and at later phase helps in defining requirements adhering to the same.

The main reasons to understand requirement can be:

Clarity and Scope Definition:
It simply defines the project scope, functionalities, constraints, and user expectations clearly, avoiding misunderstandings later in the development process.

Foundation for Design and Development:
The gathered requirements serve as the foundation for the system design, development, and testing phases. Accurate requirements ensure that the system is built as per user needs.

Cost and Time Management:
Well-defined requirements help in estimating project cost, time, and resources effectively, reducing the risk of scope creep, rework, and project failure.

Long Answer Questions: [2x8-16]
GROUP C

15.What is computer network? Explain any three types of network topologies with their advantages.
[2+6]

Ans:-

Computer network:-

A computer network, often simply referred to as a network, is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics.

Purpose of networking:-

• Networking for communication medium (have communication among people;internal or external)
• Resource sharing (files, printers, hard drives, cd-rom/)
• Higher reliability ( to support a computer by another if that computer is down)
• Higher flexibility( different system can be connected without any problems)
• Scalable (computers and devices can be added with time without changing original network.

Topology:

When we go for networking, we connect some computers in particular layout or design. This design or pattern of connection is called topology.

There are many types;

Bus topology:

A linear bus topology consists of a main run of cable with a terminator at each end (See fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear cable.

Fig. 1. Linear Bus topology

Advantages of a Linear Bus Topology

• Installation is easy and cheap to connect a computer or peripheral to a linear bus.

• Requires less cable length than a star topology.

Star topology:-

A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator (See fig. 2).
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network.
It also acts as a repeater for the data flow. This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable.

                Fig. 2. Star topology

Advantages of a Star Topology

• Easy to install and wire.

• No disruptions to the network when connecting or removing devices.

• Easy to detect faults and to remove parts.

Mesh topology

The mesh topology incorporates a unique network design in which each computer on the network connects to every other, creating a point-to-point connection between every device on the network. The purpose of the mesh design is to provide a high level of redundancy.

It needs/uses n(n-1)/2 channels(paths) and n-1 input/ output ports. If one network cable fails, the data always has an alternative path to get to its destination.

Advantages:

• Provides redundant paths between devices
• The network can be expanded without disruption to current users.

16. Write a C program to read and display employee details using a structure. [Define a structure Employee to store employee name (string), ID (integer), and salary (float)]. Write a program to input values for these fields and then display them.

Ans:

#include <stdio.h>

struct Employee 

{

    char name[50];

    int id;

    float salary;

};

int main()

{

    struct Employee emp;

    printf("Enter employee name: ");

    gets(emp.name);

    printf("Enter employee ID: ");

    scanf("%d", &emp.id);

    printf("Enter employee salary: ");

    scanf("%f", &emp.salary);

    printf("\n--- Employee Details are:---\n");

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

    printf("ID     : %d\n", emp.id);

    printf("Salary : %.2f\n", emp.salary);

    return 0;

}

OR

What is pointer? Write a C program to add two numbers using call by reference.                          [2+6]

Ans:-

Pointer:-

A pointer is a specific variable that stores the memory address in C of another variable. Rather than keeping a data value directly, a pointer keeps the address where the value is saved in memory. Because they allow us to access and change variables indirectly using their addresses, pointers are powerful.

Syntax:

return type * variable name;

Example:

int *pt;

Second part:-

#include <stdio.h>

void addNumbers(int *, int *) ;

int main() 

{

    int num1, num2;

    printf("Enter first number: ");

    scanf("%d", &num1);

    printf("Enter second number: ");

    scanf("%d", &num2);

    addNumbers(&num1, &num2);

    return 0;

}

void addNumbers(int *a, int *b) 

{

    int sum;

    sum = *a + *b;

  printf("the sum is:%d",sum);

}

THE END