2nd puc computer science model 4 question papers and answers

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

PU-II COMPUTER SCIENCE

SOLVED MODEL QUESTION PAPER 4

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

      1. What are expansion slots?

Ans: an opening in a computer where you can insert a printed circuit board.

      2. Define logic gate.

Ans:  Logic gate is an electronic circuit which operates on one or more input signals to produces an output.

      3. What is non-linear data structure?

Ans: a data structure in which a data item is connected to several other data items.

      4. Name the access specifier implicitly used in a class.

Ans: private.

      5. What is dynamic memory?

Ans: it is a memory allocated to the variable during execution of a program

      6. Define data independence.

Ans: it is an ability of a database to modify a schema definition at one level without affecting a schema in the next higher level.

      7. Who are hackers?

Ans: hackers are programmers who are more interested in gaining knowledge about computer systems and possibly use this knowledge for playful pranks.

       8. Expand FTP.

Ans: File Transfer Protocol.

       9. What is open source software?

Ans: softwares can be freely used but it does not have to be free of charge. Here the company constructing the business models around open source software may receive the payments concerning support, further development.

       10. Define web scripting.

Ans: the process of creating and embedding scripts in a web page is known as web scripting.

II. Answer any five of the following. Each question carries 2 marks. 5 x 2 = 10

      11. Draw a truth table to show X+XY=X.

Ans:

X	Y	XY	X+XY
0	0	0	0
0	1	0	0
1	0	0	1
1	1	1	1

      12. Show that 0+X=X using properties of 0’s and 1’s.

Ans: LHS= 0+X
If X=0, then, 0+X
                  =0+0
                  =0
                  =X
                  =RHS
If X=1, then, 0+X
                  = 0+1
                  =1
                  =X
                  =RHS

       13. Define polymorphism with examples.

Ans: it is an ability of the message to process in more than one form.

      14. What is a constructor? Give an example.

Ans: constructor is a special member function used to initialize data members of the class.

      15. Name any two member functions belonging to ofstream class.

Ans: put(),write(),tellp(),seekp().

      16. What is normalization? Mention its types.

Ans: normalization is a process of organizing data in a database. This includes creating tables and establishing the realtionships between those tables according to the rules designed both to protect the data and to make the database more flexible by eliminating redundancy and inconsistent dependency.

Normalization divided in to te following normal forms,

-          First Normal Form (1 NF)

-          Second Noraml Form (2 NF)

-          Third Normal Form (3 NF)

-          BCNF

      17. List DCL commands.

Ans: grant and revoke.

      18. Explain GPRS.

Ans: GPRS is the abbreviation for General Packet Radio Service. It is used in wireless communication using mobile device. With this service you can access the internet, send emails and large data, real time news, download games and watch movies.

III. Answer any five of the following. Each question carries 3 marks. 5 x 3 = 15

      19. Mention the types of motherboard.

Ans: - eXtended Technology (XT)

-          Advanced Technology (AT)

-          Baby Advanced Technology (Baby AT)

-          Advanced Technology eXtended (ATX)

      20. Explain NAND gate with logic diagram and truth table.

Ans: NAND gate produces 0 for all 1 inputs and produces 1 for other input combinations.

      21. Write an algorithm to delete an element from an 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

      22. What is new operator in C++? Give an example.

Ans: Operator that allocates memory for objects from a pool called the free store. The new operator calls the special function operator new.
Example, to allocate memory of type integer, int *iptr=new int;

      23. Explain opening a file using open () member function with syntax and example.

Ans: the syntax for opening a file for output purpose only using an object of ofstream class and open() member function is as follows:
ofstream_object.open(“filename”);
example: ofstream ofile;
ofile.open(“text.txt”);

the syntax for opening a file for input purpose only using an object of ifstream class and open()
member function is as follows:
ifstream_object.open(“filename”);
example: ifstream ifile;
ifile.open(“text.txt”);

      24. List the types of data model explain any one.

Ans: - hierarchical data model.

-          Network data model.

-          Relational data model.

      25. What is proprietary software? Write its limitations.

Ans:  proprietary software is software that is neither open nor freely available. Its use is regulated and further distribution and modification is either forbidden or requires special permission by the supplier or vendor. Source code of proprietary software in normally not available.

      26. Write HTML program to show the use of list items.

Ans: <HTML>

<BODY>

<OL>

<LI>APPPLE</LI>

<LI>MANGO</LI>

<LI>KIWI</LI>

</OL>

</BODY>

IV. Answer any seven of the following. Each question carries 5 marks. 7 x 5 = 35

      27. Using K-map, simplify the following expressions in four variables, W,X,Y,Z.

       m₁,m₃,m₅,m₇,m₉,m₁₁,m₁₃,m₁₅

Ans: 

      28. Write an algorithm to PUSH and POP an element from the stack.

Ans: An algorithm for PUSH() Operation

Step 1: if TOP=N then

                  PRINT “stack is full”

                  Exit

                  End of if

      Step 2: TOP=TOP+1

      Step 3: STACK[TOP]=ITEM

An algorithm for POP() Operation

Step 1: if TOP=o then

                  PRINT “Stack is empty”

                  Exit

Step 2: ITEM=STACK[TOP]

Step 3: TOP=TOP-1

      29. List the applications of queues.

Ans: -Simulation.
- Multi-programming platform systems.
- Various features of operating system.
- Different types of scheduling algorithm.
- Printer server routines

      30. Describe the basic concepts of object oriented programming.

Ans: Following are the major characteristics of OOPs
- Objects
- Classes
- Data abstraction
- Data encapsulation
- Inheritance
- Overloading
- Polymorphism
- Dynamic binding
- Message passing

  Ø  Objects: An object may be a person, place or a table of data. An object is a collection of data members and function members.

Ex: Apple, Orange, Mango etc are the objects of the class fruit

Objects take memory and have addresses
                                                                   Object-1 (Student)

     

  Ø  Classes: A class is a group of objects having similar characteristics. Once a class is defined, any number of objects of that class are created
      Ex 1: man and woman belongs to the same class called Human Being.
      Ex 2: planets, sun, moon are members of class solar system.

  Ø  Data abstraction: Abstraction is a process of representing essential features without including background details or explanations.

  Ø  Data encapsulation: data encapsulation combines both data and functions in a single unit called class. Data encapsulation prevents data from direct access. The data can be accesses only through functions present inside the class definition. Data encapsulation enables data hiding or information hiding

                                                                            Object

  Ø  Inheritance: The concept of inheritance provides the use of reusability. This means that we can add additional features to the existing class without modifying it. Thus the process of acquiring properties of one class to another is called inheritance. The existing class is known as base class and the new class obtained is called derived class.
      The derived class shares some of the properties of the base class. Therefore a code from a base class can be reused by a derived class.

  Ø  Overloading: There are two types of overloading:
      a) Operator overloading: when existing operator operates on new data type is called operator overloading.
      b) Function overloading: Two or more functions have same name but different number of arguments or data type of arguments. Function overloading is a process of defining same function name to carry similar types of activities with various data items.

  Ø  Polymorphism: it is a process where a function can take multiple forms based on the type of arguments, number of arguments and data type of return value
      The ability of an operator and function to take multiple forms is known as polymorphism

Ex: int addition(int a, int b);

       int addition( float a, float b);

Consider the addition operation. In addition of two numbers the result is the sum of two numbers.

In addition of two strings the operation is string concatenation. When an operator behaves differently based on operands, then it is said that operator is overloaded. Similarly when same function is used for multiple tasks in the same program by changing argument type and number, it is known as function overloading

  Ø  Dynamic binding: binding is a process of connecting one program to another. Dynamic binding is a process of connecting one program to another during execution (when function is called).

  Ø  Message passing: a message for an object is request for execution of procedure. Message passing involves specifying the name of object, the name of the function and the information to be sent

      31. Explain array of objects with programming example.
      Ans: An array having class type elements is known as array of objects. An array of objects is declared after class definition and is defined in the same way as any other array.
      Ex:
      class employee
      {
      char name[15];
      int age;
      float salary;
      public:
      void getdata()
     {
      cout<<”Enter the name of employee: ”;
      cin>>name;
      cout<<”Enter the age of an employee: ”;
      cin>>age;
      cout<<”Enter the salary: ”;
      cin>>salary;
      }
      void putdata()
     {
      cout<<”Name: ”<<name;
      cout<<”Age: ”<<age;
      cout<<”Salary: ”<<salary;
      }
      };
      void main()
      {
      employee emp[3];
      for(int i=0;i<3;i++)
      {
       emp.getdata();
       emp.putdata();
       getch();
      }

      32. Define inline function. List the reasons for inline function may not work some times.

Ans: function which is used to replace the function call by function definition is called inline function.
The inline function may not work for some times for one of the following reasons:
- The inline function definition is too long or too complicated.
- The inline function is recursive.
- The inline function has looping constructs.
- The inline function has a switch or goto.

      33. Explain features and disadvantages of default constructor.

Ans: Features of default constructors are,
- Default constructor automatically invokes when object is created
- All objects of the class are to be initialized to same set of values by the default constructor
- If different objects are to be initialized with different values, it cannot be done using default constructor.
Disadvantages of default constructor are,
- When many objects of the same class are created, all objects are initialized to same set of values by default constructor.
- It is not possible to initialize different objects with different initial values using default constructor.

      34. Describe virtual base classes and abstract classes with example.

Ans: consider a situation where the program design would require one base class call it A and two derived classes namely B and C, which are inherited from the base class A. further, derived class D is created from B and C. 

When two or more objects are derived from a common base class, we can prevent multiple copies of the base class being present in an object derived from those objects by declaring the base class as virtual when it is being inherited. Such a base class is known as virtual base class. This can be achieved by preceding the base class name with the word virtual

Ex: class A

      {

      __________

      __________

};

class B: virtual public A

{

____________

____________

};

class C: virtual public A

{

____________

____________

};

class D: public B, public C

{

____________

____________

};

      35. Explain any five applications of database.

Ans: Following are the list of database applications
- Banking: used in banks for customer, accounts, loans and banking transaction information
- Water meter billing: meter number and all the details of the customer is stored in the database
- Rail and airlines: for reservations and schedule information
- Colleges: used to store students information, course registrations and grades
- Human resources: used to store information about employees, salaries, payroll taxes and benefits etc

      36. Describe any five comparison operators with 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. What is virus? Explain the types of viruses.

Ans: “computer virus is a malicious program that disrupts the normal functioning of the computer.”
File infectors: these types of viruses either infect executable files or attach themselves to a program file and create duplicate files.

Boot sector viruses: install themselves on the beginning tracks of a hard drive or the Master Boot Record or simply they change the pointer to an active boot sector.

Macro Viruses: infect data files like electronic spread sheets of databases of several software packages.

Network Viruses: these virus use protocols and commands of computer network to spread themselves on the network. Generally they use email or any data transfer files to spread themselves on the network.