2nd puc computer science model 5 question papers and answers

2nd puc computer science model question papers and answers,2nd puc computer science solved model question papers

PU-II COMPUTER SCIENCE

SOLVED MODEL QUESTION PAPER 5

PART - A

I. Answer all the questions. Each question carries 1 mark. 10 x 1 = 10

1. What is Data bus?

Ans: a bus is a set of wires and each wire carry one bit of data.

2. Write the standard symbol for two input NOR gate.

Ans:

3. What is sorting?

Ans: the process of arrangement of data items in ascending or descending order is called sorting

4. Define the term ‘topology’ of computer networks.

Ans: the actual appearance or layout of networking.

5. Which symbol is used as address operator in C++?

Ans: Address of (&)

6. What is a record?

Ans: A single entry in a table is called a record.

7. What is a virus?

Ans: computer virus is a malicious program that requires a host and is designed to make a system sick.

8. Name any one non-linear data structure.

Ans: trees and graphs.

9. Mention any one type of e-commerce.

Ans: business to business, business to consumer.

10. Expand ISA.

Ans: Industry Standard Architecture.

PART – B

II. Answer any five questions. Each question carries 2 marks. (5 X 2 = 10)

11. State and prove Involution law.

Ans:

it states that the complement of a variable is complemented again, we get the same variable.

~(~X)=X.

proof: if x=0 then ~x=1 and ~(~x) = ~1 = 0 = x

if x=1 then ~x=0 and ~(~x) = ~0 = 1 = x

12. Prove X.(X+Y)=X.

Ans: : LHS = X.(X+Y)

= X.X+X.Y

= X+XY

= X(1+Y)

= X.1

= X

=RHS

13. What are minterms and maxterms?

Ans: Minterms: “The sum of all the literals with or without bar in the logic system is called minterms”.
Maxterms: “The product of all the literals with or without bar in the logic system is called maxterms”.

14. What is destructor? Write the symbol used for destructor.

Ans: Destructor is a special member function which is used to de-allocate memory location occupied by the object created by the constructor.

Symbol used for destructor is tilde (~).

15. Mention the types of data files.

Ans: text file and binary file

16. What is Database Management System? Give an example of DBMS software.

Ans: DBMS is a software that allows creation, definition and manipulation of database.

Example: Oracle, Sybase, DB2, Ingress, Informix, MS-SQL server

17. Write any two member functions belonging to ofstream class.

Ans: put(), write().

18. Define:

a) Client

b) Server.

Ans: Client is a computer system that seeks data and information from the other computer.

Server is a computer system that provides data and information to the other computer.

PART – C

III. Answer any five questions. Each question carries 3 marks. (5 X 3 = 15)

19. Explain any three I/O ports.

Ans: - serial port or communication (COM) port: it is used to connect communicating device like modem and mouse. This transfers one bit data at a time. It needs a single wire to transmit 1 bit of data. Hence it takes 8 times longer to transfer a byte. There are two types of com ports, the 8-pin ports and 25-pins ports.

- Parallel port: it is used to connect external input/output devices like printers or scanners. Data transfer is usually one byte (8-bits) at a time and it has 25 pins.

- IDE (Integrated Digital Electronics) port: IDE devices like CD-ROM drives or hard disk drives are connected to the mother through the IDE port.

- USB (Universal Serial Bus) port: external peripheral devices such as printers, scanners, digital cameras, web cameras, speakers etc. USB supports a data speed of 12 megabits per second, supporting up to 127 devices.

20. What is meant by shareware? Write its limitations.

Ans: software made available with the right to redistribute copies, but it is stipulated that if one intends to use the software, often after a certain period of time, then a license fee should be paid.

Limitations of shareware:

- In shareware the source code is not available.

- Modifications to the software are not allowed.

21. Give the memory representation for two dimensional array using Column Major Ordering.

Ans:
In this method the elements are stored column wise, i.e. m elements of first column are stored in first m locations, m elements of second column are stored in next m locations and so on. E.g.
A 3 x 4 array will stored as below:

22. Give the advantages of pointer.

Ans: - It is possible to write efficient programs

-Memory is utilized properly

-Dynamically allocate and de-allocate memory

-Easy to deal with hardware components

-Establishes communication between program and data

23. Explain the use of new and delete operators in pointers.

Ans: These operators allocate memory for objects from a pool called the free store. The new operator calls the special function operator new and the delete operator calls the special function operator delete

Example, to allocate memory of type integer, int *iptr=new int;

To allocate memory of type float, float *fptr=new float;

To allocate memory of type double, double *dptr=new double;

Releasing dynamic memory using delete as: delete iptr;

24. Explain the advantages (features) of DBMS.

Ans: in the database approach, the data is stored at a central location and is shared among multiple users. Thus, the main advantage of DBMS is centralized data management. The advantages of centralized database system are as follows:

-Controlled data redundancy: elimination of duplication of data item in different files ensures consistency and saves the storage space. The redundancy in the database cannot be eliminated completely as there could be some performance and technical reasons for having some amount of redundancy.

-Enforcing data integrity: data integrity refers to the validity of data and it can be compromised in a number of ways.

-Data sharing: the data stored in the database can be shared among multiple users or application programs. It is possible to satisfy the data requirements of the new applications without creating any additional data or with minimal modification.

-Ease of application development: the application programmer needs to develop the application programs according to user’s needs. The other issues like concurrent access, security, data integrity etc are handled by the RDBMS itself.

-Data security: since the data is stored centrally data security checks can be carried out whenever access is attempted to sensitive data. To ensure security, a RDBMS provides security tools such as used codes and passwords. Different checks can be established for each type of access like addition, modification, deletion etc to each piece of information in the database.

-Multiple user interfaces: For various users having different technical knowledge DBMS provides different types of interfaces such as query languages, application program interfaces, and graphical user interfaces (GUI).

-Backup and recovery: RDBMS provides backup and recovery subsystem that is responsible for recovery from hardware and software failures. For example, if the failure occurs in between the transaction, the RDBMS recovery subsystem either reverts back the database to the state to the previous state of the transaction or resumes the transaction from the point it was interrupted so that its complete effect can be recorded in the database.

25. What is e-commerce? Explain any two types.

Ans: e-commerce is the trade of goods and services with the help of telecommunications and computers.

- Business to Business (B2B): Exchange of goods, service and information between two business partners. Ex: Ebay.com

- Business to Consumer: (B2C): Exchange of goods, service and information from business to consumer. Ex: paytm.com

- Consumer to Business: (C2B): Exchange of goods, service and information from consumer to business. Ex: guru.com, freelancer.com

- Consumer to Consumer: (C2C): Exchange of goods, service and information between two consumers. Ex: olx.in

26. Expand UPS. Explain the types of UPS.

Ans: electronic components of a computer system require continuous supply of electric current for their operations to prevent them from the failures, break down or shutdown.
There are two types of power supply connected to a computer system; they are Switched Mode Power Supply (SMPS) and Uninterruptable Power Supply (UPS).

- SMPS: it converts AC power into DC power. It is a metal box in the rear of the system. It contains the power card plug and a fan for cooling, because it generates a lot of heat. SMPS with a power of 300 watts is needed. It converts 230 volts of AC to 5 to 12 DC volts and the wattage is around 180 to 300 watts, 450 watts and 500 watts.

- UPS: An UPS is a power supply that includes a battery to maintain power in the event of a power failure. An UPS keeps a computer running for several minutes to few hours after a power failure, enabling us to save data the is in RAM and then shut down the computer.
There are two types of UPS: Online UPS and standby UPS.

- Online UPS: it provides continuous power to the system from its own inverter when the power goes off. For a PC with color monitor 15”, requires an UPS of 500 VA and for a PC with color monitor 17”, requires an UPS of 600 VA.

- Standby UPS or Offline UPS: it monitors the power line and switches to battery power as soon as it detects a problem. The switch over to battery however, can require several milliseconds, during which time the computer is not receiving any power.

PART – D

IV. Answer any seven questions. Each question carries 5 marks. (7 X 5 = 35)

27. Write an algorithm to insert an element into a queue.

Ans: Step 1: if REAR=N then

PRINT “overflow”

Exit

Step 2: if FRONT=NULL then

FRONT=0

REAR=0

Else

REAR=REAR+1

Step 3: QUEUE[REAR]=ITEM

Step 4: return

28. Reduce

F(A,B,C,D)=∑(0,2,4,6,10,14) USING K-MAP.

Ans:

29. Give the applications of stack.

Ans: - stack is used to reverse a word.

- It is used in undo mechanism in text editors.

- Conversion of decimal number into binary.

- To solve tower of hanoi.

- Conversion of infix expression into prefix and postfix.

- Quick sort.

- Run time memory management.

30. Write the rules for to be followed in writing constructor function in C++.

Ans: - A constructor name is always same as that of the class name

- There is no return type for the constructors not even void

- A constructor should be declared in public section

- A constructor is invoked automatically when objects are created

- It is not possible to refer to the address of constructors

- The constructors make implicit calls to the operators new and delete when memory allocation is

required.

31. What is a class? Write its declaration syntax and example.

Ans: a class is a collection of object of similar type that share some common properties among them.

Syntax of a class:

class class_name

{

private: data member;

function member;

protected: data member;

function member;

public: data member;

function member;

};

Example: class student

{

private: int rollno;

char name[15];

float percentage;
public: void getdata();
void putdata();
};

32. What is a friend function? Write the characteristics of a friend function.

Ans: friend function is a non-member function that has full access right to private and protected members of the class.

Characteristics of a friend function are as follows:

- A friend function has full access right to the private and protected members of the class

- A friend function cannot be called using the object of that class. It can be invoked like any normal

function

- A friend function can be declared anywhere in the class and it is not affected by access specifiers

(private, protected and public)

- They are normal external functions given special access privileges

- The function is declared with keyword friend. But while defining friend function it does not use

either friend or :: operator.

33. What is copy constructor? Explain with syntax and programming example.

Ans: The copy constructor is a constructor which creates an object by initializing it with an object of the same class.

The copy constructor is used to −

Initialize one object from another of the same type.
Copy an object to pass it as an argument to a function.
Copy an object to return it from a function.

Syntax: x a1; //x is a class and a1 and a2 are objects of the same class

x a2=a1;

#include<iostream.h>

#include<conio.h>

class copy

{

int var;

public: copy(int temp)

{

var=temp;
}
int calculate()
{
int fact,i;
fact=1;
for(i=1;i<=var;i++)
fact=fact*i;
retrun fact;
}

};

void main()

{

int n;

cout<<”Enter the number: ”;

cin>>n;

copy obj(n);

copy cpy=obj;

cout<<”Before copying : ”<<n<<”!=”<<obj.calculate()<<endl;

cout<<”After copying : ”<<n<<”!=”<<cpy.calculate()<<endl;

}

34. Explain network securities in detail.

Ans: Authorization: Authorization is the process of allowing an authenticated users to access the resources by checking whether the user has access rights to the system. Authorization helps you to control access rights by granting or denying specific permissions to an authenticated user.

- Authentication: Authentication is the process of verifying the identity of a user by obtaining some sort of credentials and using those credentials to verify the user's identity. If the credentials are valid, the authorization process starts. Authentication process always proceeds to Authorization process.

- Encrypted smart cards: Confidentiality is the use of encryption to protect information from unauthorized disclosure. Plain text is turned into cipher text via an algorithm, then decrypted back into plain text using the same method.
Cryptography is the method of converting data from a human readable form to a modified form,
and then back to its original readable form, to make unauthorized access difficult.

- Biometric systems: it involves unique aspects of a person’s body such as finger prints, retinal patterns, etc to establish his/her identity.

- Firewall: A firewall is a network security system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Network firewalls are frequently used to prevent unauthorized internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.

35. Explain the differences between manual data processing and computerized (electronic) data processing.

Ans:

Manual data processing	Computerized electronic data processing
The volume of data, which can be processed, is limited.	The volume of data which can be processed can be very large.
It requires large quantities of paper.	Reasonable, less amount of paper is used.
The speed and accuracy is limited.	The job executed is faster and accurate.
Labor cost is high.	Labor cost is economical.
Storage medium is paper.	Storage medium is secondary storage medium.

36. Explain any five relational/comparison operators in SQL with suitable examples.

Ans: consider a=10 and b=20

Operator	Description	Example
=	Checks if the values of two operands are equal or not, if yes then condition becomes true.	(a=b) is not true
!=	Checks if the values of two operands are equal or not, if values are not equal then condition becomes true.	(a!=b) is true
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(a>b) is not true
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(a<b) is true
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(a>=b) is not true
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(a<=b) is true

37. Explain briefly the types of inheritance.

Ans: - Single inheritance: if a class is derived from a single base class, it is called as single inheritance.

- Multilevel inheritance: the classes can also be derived from the classes that are already derived. This type of inheritance is called multilevel inheritance.