2nd puc computer science question papers with answers 2019

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PU-II COMPUTER SCIENCE 2019 SOLVED QUESTION PAPER

PART – A

Answer all the questions.
Each question carries 1 mark. (10 X 1 = 10)

      1) Expand the term DDRRAM.
      Ans: Double Data Rate Random Access Memory.

      2) Write the standard symbol for two input NOR gate.
      Ans:

      3) Give an example for non-primitive data structure.
      Ans: arrays, lists, files.

      4) What is meant by data encapsulation?
      Ans: 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.

      5) Which symbol is used as address operator in C++?
      Ans: Address of (&)

      6) Define tuple.
      Ans: tuple is a single entry in the table.

      7) What is Wide Area Network (WAN)?
      Ans: the network spread across the countries is known as Wide Area Network.

      8) What is ring topology?
      Ans: each node is connected to two and only two neighboring nodes or nodes are connected in a circular fashion.

      9) Mention any one type of e-commerce.
      Ans: business to business, business to consumer.

      10)  What is free hosting?
      Ans: hosting web pages with no cost is called free hosting.

PART – B

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

      11)  Prove that X.X' = 0 by perfect induction method.
      Ans: if X=0 then X.X’ = 0.0’ = 0.1 = 0 = RHS

   if X=1 then X.X’ = 1.1’ = 1.0 = 0 = RHS

      12)  Prove X.(X+Y) = X algebraically.
      Ans: LHS = X.(X+Y)

            = X.X+X.Y

            = X+XY

            = X(1+Y)

            = X.1

            = X

            =RHS

      13)  Give any two applications of OOP.

Ans: 

- Computer graphic applications

- CAD/CAM software

- Object oriented database

- User interface design such as windows

- Real-time systems

- Simulation and modeling

- Artificial intelligence and expert systems

      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 any two ofstream functions.

      Ans: write(), put(), tellp().

      16)  Define primary key and candidate key.
      Ans: Primary key: a column or combination of columns which uniquely identifies each row in the table.
      Candidate key: A super key with no repeated attribute is called candidate key.

       17)  Differentiate between DELETE and DROP commands in SQL.
       Ans:

DELETE	DROP
1.      DELETE command is used to delete the content of the table.	1.      DROP command is used to delete the entire table along with the content.
2.      Syntax: delete from table_name where     [column_name=value];	2.      Syntax: DROP TABLE table_name.

      18)  Briefly explain circuit switching technique.
      Ans: in circuit switching technique, complete physical connection between two computers is established and then data are transmitted from source computer to the destination computer.

PART – C

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

      19)  What is the purpose of UPS? Mention different types of UPS.
      Ans: 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

      20)  Explain the working of two input NAND gate with logic symbol and truth table.
      Ans: if all of the inputs are 1, then the output produced is 0.

      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)  Define an array of pointers. Give an example.
      Ans: An array of pointers means that it is a collection of addresses.
      Example: int *iptr[5];
      int i=10,j=20,k=30,l=40,m=50;
      iptr[0]=&i;       *iptr[0]=10;
      iptr[0]=&j;       *iptr[0]=20;
      iptr[0]=&k;      *iptr[0]=30;
      iptr[0]=&l;       *iptr[0]=40;
      iptr[0]=&m;     *iptr[0]=50;

      23)  What is data file? Differentiate between text file and binary file in C++.
      Ans: A data file is a computer file which stores data to be used by a computer application or system.
      1. Binary form: 
       - The information stored is in the form of Bits
       -  No delimiters are used for a line
       -  No translation required

      2.   Text form:

       - The information stored is in the form of ASCII characters.

      -  Each line of text is terminated with a special character known as EOL (End Of Line) character.

      - Internal translation occurs.

      24)  Mention different database models explain any one.
      Ans: - Hierarchical model
      - Network model
      - Relational model
      - Relational model: the relational model was developed by E.F.Codd in 1970. In relational model there are no physical links. All data is maintained in the form of tables (generally known as relations) consisting of rows and columns. Each row or record represents an entity and a column or field represents an attribute of the entity. Oracle, Sybase, DB2, Ingress, Informix, MS-SQL server are the examples of DBMSs.
      In this model, data is organized in two-dimensional tables called relations. The tables or relations are related to each other.

Relational model of database

       25)  Write any three advantages of e-Commerce.
       Ans: - Easier entry to new markets.
       - Global participation.
\      - Optimization of resources.
       - Reduces time for business transactions.
       - Improved strategic planning.       

       26)  Explain any three text formatting tags in HTML.
       Ans: <B> is used to make text Bold.
       <U> is used to draw underline.
        <I> is used to make text italics.

PART – D

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

      27)  Given Boolean function.

F(a,b,c,d) = ∑(0,1,2,3,4,6,8,10,12,14).

Reduce it by using Karnaugh map.

Ans: 

      28)  Write an algorithm to delete an element from a queue data structure.
      Ans: Step 1: if FRONT=NULL then

                     PRINT “underflow”           

                     Exit

   Step 2: ITEM=QUEUE[FRONT]

   Step 3: if FRONT=REAR then

                  FRONT=0

                  REAR=0

                  Else

                  FRONT=FRONT+1

   Step 4: return

      29)  What is primitive data structure? Explain different operations performed on primitive         data structures.
      Ans: “data structures that are directly operated upon by machine-level instructions are known as primitive data structures.”
      Operations on primitive data structures,
      - Create: create operation is used to create a new data structure. This operation reserves memory space for the program elements. It can be carried out at compile time and run-time.
      For example, int x;
      
      - Destroy: destroy operation is used to destroy the data structures from the memory space. When the program execution ends, the data structure is automatically destroyed and the memory allocated is eventually de-allocated. C++ allows the destructor member function destroy the object.

      - Select: select operation is used by programmers to access the data within data structure. This operation updates the data.

      - Update: update operation is used to change data of data structures. An assignment operation is a good example of update operation.

For example, int x=2;                    here, 2 is assigned to x.

Again, x=4;                                   4 is reassigned to x. the value of x now is 4 because 2 automatically replaced by 4. 

      30)  Mention any five advantages of OOP over procedural programming languages.

Ans: 

- 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.

      31) Explain member function outside class definition. Give an example.

Ans: To define member functions written outside the class definition replaced by actual                  function definition outside the class.

 Ex: class room

  {

  int length;

  int breadth;

  public: void getdata();

               void putdata();

        };

  void room::getdata()
 {

 cin>>length;

 cin>>breadth;

       }

       void room::putdata()

 {

 cout<<length;

 cout<<breadth;
}

The symbol :: is known as scope resolution operator. The scope resolution operator identifies            the function as a member of particular class. The use of scope resolution operator implies that            these member functions are defined outside the class.

      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)  Give the definition for a constructor and mention the rules for writing constructor                 function.
      Ans: constructor is a special member function used to initialize the data members of the class
      Rules for writing a constructor function are as follows
      - 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.

      34)  What is inheritance? Briefly explain hierarchical and hybrid inheritance.
      Ans: inheritance is a process of acquiring properties from parent class to child class.

- Hierarchical inheritance: if a number of classes are derived from a single base class, it is
               called as hierarchical inheritance.  

 - Hybrid inheritance: it is a combination of Hierarchical and Multiple inheritance.

      35)  Briefly explain the advantages of database system.
      And: 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

      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)  Define the following.
      a) SIM
      Ans: Subscriber Identity Module is a tiny computer chip gives a unique phone number. It has emory, processor and the ability to interact with the user. It has 16 to 64 Kb of memory to store hundreds of personal phone numbers, text messages and other data.

      b) SMS
      Ans: Short Message Service (SMS) is the transmission of short text messages to and from a mobile phone.

      c) Wi-fi
      Ans: Wi- Fi refers to Wireless Fidelity, which lets you connect to the internet without a direct line from your PC to the ISP.

      d) Chatting
      Ans: Chat is a text-based communication that is live or in real-time. For example, when talking to someone in chat any typed text is received by other person immediately.
      
       e) Video conference.
       Ans: video conference is two-way interactive communication that is similar to a telephone call but over video.

       
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