2nd puc computer science question papers with answers 2017

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PU-II COMPUTER SCIENCE MARCH 2017 SOLVED QUESTION PAPER

PART - A

Note: 
i) Answer All the questions.

ii) Each question carries ONE mark. (10 X 1 = 10)

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

      2. Write the standard symbol of NOT gate.
      Ans:

      3. Define linked list.
      Ans: a linked list is a linear collection of data elements called nodes and the linear order is given by means of pointers. Each node contains two parts fields: the data and reference to the next node.

      4. What is a member function?
      Ans: function that operates on data is called member function.

      5. How to declare a pointer?
      Ans: Declaration:
      data type  *pointer_variable, common_variable_name;

      6. Define data.
      Ans: data is raw fact, figure or statistics that is to be processed to get meaningful information.

      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. Expand TCP.
      Ans: Transmission Control Protocol

      9. What are browsers?
      Ans: a web browser is a www client that navigates through the www and displays web pages. Internet Explorer and Netscape Navigator are the example for web browser.

      10. Write the purpose of HTML.
      Ans: HTML is used to write content of web pages and make it available across the world.

PART – B

Note:
(i) Answer any FIVE of the questions.

(ii) Each question carries TWO 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 algebraically : (x+y).(x+z)=x+y.z
      Ans: LHS = (x+y)(x+z)

            = x.x+x.z+x.y+y.z

            = x+xz+xy+yz

            = x(1+z+y)+yz

            = x.1+yz

            = x+yz

            = RHS

      13. What is:
      (a) Polymorphism
      Ans: a function can take multiple forms based on the type of arguments, number of arguments and data type of return value
      (b)   Message passing
      Ans: a message for an object is request for execution of procedure. Message passing involves specifying the name of object, name of the function and the information to be sent

       14.What is a constructor? Give one example.
       Ans: constructor is a special member function used to initialize the data members of the class

 #include<iostream.h>

 #include<conio.h>

 class c

 {

 int a,b;

 public: c()

{

a=10;

b=20;

}         

void display()

{

cout<<a<<b;

}

};

void main()

{

c obj;

obj.display();

getch();

}

      15. Mention the types of data files.
      Ans: text file and binary file

 

      16. Write any two applications of database.
      Ans: banks, stocks, water billing, airlines etc.

      17. Mention the relational operators in SQL.
      Ans: =, <>, <, >, <=, >= etc.

      18.  What is meant by client and 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

Note:
(i) Answer any FIVE questions.

(ii) Each question carries THREE 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 NAND gate? Write its standard symbol and truth table.
       Ans: NAND gate is NOT AND gate. If all the inputs are 1 then the output produces 0 for all 1 inputs and produces 1 for other input combinations.

       21.  Write any three applications of stack.
       Ans:  - conversion of decimal number into binary.
       - To solve Tower of Hanoi.
       - Expression evaluation and syntax parsing.
       - Conversion of infix expression into postfix.

       22.  Explain dynamic memory allocation of a variable.
       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;

      23. Explain any three member functions belonging to ofstream.
      Ans: put(): the put() member function writes a single character to the associated stream.
      Syntax: ofstream_object.put(ch);
      Ex: char ch=’a’;
      ofstream fout(“text.txt”);
      fout.put(ch);
      write(): the write member function is used to write a binary data to a file.
      fout.write((char *)&variable,sizeof(variable));
      ex: student s;
      ofstream fout(“text.txt”,ios::binary);
      fout.write((char *)&s,sizeof(s));
      tellp() member function: the tellp() member function return current position of the put pointer.
      Syntax: int position;
      position=fout.tellp();

      24. Mention the data types available in DBMS.
      Ans: int, numeric, float, real, datetime,date, time, char, varchar.

      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.  Write any three text formatting functions in HTML with their purpose.
      Ans: <B> is used to make text Bold.
      <U> is used to draw underline.
      <I> is used to make text italics.

PART – D

Note:
(i) Answer any SEVEN questions.
(ii) Each question carries FIVE marks. (7 X 5 = 35)

      27.  Reduce

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

Ans:

      28. Write an algorithm to delete an element from the array.
      Ans: Step 1: item=A[P]

   Step 2: for I=P to N-1

                  A[I]=A[I+1]

                  End of for

   Step 3: N=N-1

   Step 4: exit

29.  Define two-dimensional array. Write its memory representation in

(a) Row-major order. 

(b) Column-major order.

 Ans: Each element in an array can be accessed by two subscripts is known as two dimensional array.(a)    Row-major order.

      In this method the elements are stored row wise, i.e. n elements of first row are stored in first n locations, n elements of second row are stored in next n locations and so on. E.g.

      A 3 x 4 array will stored as below:

(b)   Column-major order.

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:

      30. Write the advantages and disadvantages of OOPs.

      Ans: Advantages of OOPs

      - Using class and objects, programs are modularized

      - Linking code and object allows related objects to share common code. This reduces code duplication and code reusability

      - As the data is encapsulated along with functions, the non-member functions cannot access or modify data. Thus, providing data security

      - Complexity of the program development is reduced through the use of inheritance

      - Reduces time, as creation and implementation of OOP code is easy

      - Through message passing OOP communicates to the outside system

      Disadvantages of OOPs

      - OOP software is not having set standards.

      - The adaptability of flow diagrams and object oriented programming using classes and objects is a complex process.

      - To convert real world problem into an object oriented model is difficult.

      - The classes are overly generalized.

       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.  Write the characteristics of friend function.
      Ans: - 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 a parameterized constructor? Give one example. Write its features.
      Ans: A constructor that takes one or more arguments is called parameterized constructor. Using this constructor it is possible to initialize different objects with different values. The parameters are used to initialize the object.

#include<iostream.h>
#include<conio.h>
class num
{
int a,b;
public: num(int m,int n)
{
a=m;
b=n;
}
void display()
{
cout<<”A=”<<a<<”B=”<<b
}
};
void main()
{
num n;
n.num(10,20);
n.display();
getch();
}
Features of parameterized constructor are as follows:
- The parameterize constructor can be overloaded.
- For object created with one argument, constructor with only one argument is invoked and executed.
- The parameterized constructor can have default arguments and default values.

      34.  What is inheritance? Explain:
      Ans: the process of acquiring properties of one class to another is called inheritance.
      (a) Single level inheritance
         Ans: Single inheritance: if a class is derived from a single base class, it is called as single inheritance.

      (b)   Multi level inheritance.
      Ans: Multilevel inheritance: the classes can also be derived from the classes that are already derived. This type of inheritance is called multilevel inheritance.

      35.  Explain Random Direct access file organization. Write its advantage and disadvantage.
      Ans: random access method: records are stored on disk by using a hashing algorithm. The key field is fed through hashing algorithm and a relative address is created. This address gives the position on the disk where the record is to be stored. The desired records can be directly accessed using randomizing procedure or hashing without accessing all other records in the file.
      Advantages:
      - The retrieval of records is quick and direct.
      - Transactions need not be stored and placed in sequence prior to processing.
      - Best used for online transaction.
      Disadvantages:
      - Overhead of Address generation due to hashing function.
      - Less efficient in the use of storage space than sequentially organized files.

       36.  What is DDL? Write the syntax and example for CREATE and DROP command.
      Ans: DDL defines the conceptual schema providing link between the logical and the physical structure of the database.
      Syntax for CREATE table:
      CREATE TABLE table_name(column1 datatype,column2 datatype,…column datatype);
      Example: create table student(rollno number(3),name varchar(20));
      
      Syntax for DROP command:
      DROP TABLE table_name;
      Example: DROP TABLE student;

      37.  Define topology. Explain any two network topologies.
      Ans: The layout of networking is called as Topology.
      - Bus topology or linear topology: this consists of a single length of the transmission medium onto which the various nodes are attached. The transmission from any station travels the length of the bus, in both directions, and can be received by all other stations. The bus has terminators at either end which absorb the signal, removing it from the bus

- Ring topology or circular topology: In this topology each node is connected to two and only two neighboring nodes and is transmitted to another. Thus data travels in one direction only, from node to node around the ring. After passing through each node, it returns to the sending node, which removes it.

- Star topology: this topology consists of a central node to which all other nodes are connected by a single path.

In star topology, every node (computer workstation or any other peripheral) is connected to a central node called a hub or switch. The switch is the server and the peripherals are the clients.

Advantages

• ·Star networks are very reliable because if one computer or its connection breaks it doesn’t affect the other computers and their connections

Disadvantages

• An expensive network layout to install because of the amount of cables needed
• If the server crashes or stops working then no computers will be able to access the network

- Tree topology: In telecommunication networks, a tree network is a combination of two or more star networks connected together. Each star network is a local area network (LAN) in which there is a central computer or server to which all the workstation nodes are directly linked. The central computers of the star networks are connected to a main cable called the bus. Thus, a tree network is a bus network of star networks.

- Mesh topology: A mesh network is a network topology in which each node relays data for the network. All mesh nodes cooperate in the distribution of data in the network. 

The Mesh topology is commonly used in large inter networking environments with stars, rings and buses attached to each node.