Free ISC sample paper 2021

ISC Class 12 Sample Paper 1 Standard: 12 Subject: Computer Max Marks: 70 Max. Time 3 hours ------------------------------------------------------------------------------------------------------------------------------------------- Answer all questions in Part I (compulsory) and six questions from Part-II, choosing two questions from Section-A, two from Section-B and two from Section-C. All working, including rough work, should be done on the same sheet as the rest of the answer. The intended marks for questions or parts of questions are given in brackets [ ]. ------------------------------------------------------------------------------------------------------------------------------------ PART I Answer all questions Question 1. [1X5=5] (a) State the difference between an interface and a class. (b)Verify using the truth table, if (X=>Y).(Y=>X) is a tautology, contradiction or contingency. (c) What is an abstract class? (d) Show how a NAND gate can be used to construct an OR gate. (e) Define inheritance. How is it useful in programming? Question 2. [2 x 5=10] (a) State the difference between Function Overloading and Function Overriding. (b) Convert the following expression F(X,Y,Z)=XY+Y’Z into minterms. (c) Simplify the following expression using law of Boolean algebra. At each step clearly state the law used for simplification. xy+xz+xyz (d) State the differences between a constructor and a function. (e) For an array of real numbers x [-15….10, 15….40] find the address of x [5,20 ], if x [0] [0] is stored in location 1500 in the column major order. Assume that each element requires 1 bytes. Question3. The following is a function of some class. What will be the output of the function display( ) when the value of val is equal to 6?Show the dry run / working. [5] int display (int val) { if(val==0) return 0; else returnval+ display(val-1); } 1 Part II Answer six questions in this part, choosing two questions from Section A, two from Section B and twofrom Section C. Section A Answer any two questions Question 4. a) Given the Boolean function: F (A, B, C, D) = Σ (0, 1, 2, 5, 8, 9, 10) (i) Reduce the above expression by using 4 - variable K-Map, showing the various groups (i.e.; octal, quads and pairs). [4] (ii) Draw the Logic gate diagram of the reduced expression. Assume that the variable and their complements are available as inputs. [1] b) Given G(X,Y,Z,W)= π(0,2,4,6,8,9,10,11) (i) Reduce the above expression by using 4 variable Karnaugh map, showing the various groups (i.e. Octal, quads and pairs). [4] (ii) Draw the logic gate diagram for the reduced expression. Assume that the variables and their complements are available as inputs. [1] Question 5 (a) Draw a logic diagram for the following function using only NOR gates: [3] (A, B, C) = (A’ + B’) . (B + C’) (b) Convert the following expression into canonical Sum-Of-Product form: [3] (X, Y, Z) = X’.Y + X’.Y’ + Y.Z’ (c) What is a half adder? Draw the truth table, derive its Boolean expression and draw a logic diagram for half adder. [4] Question 6 (a) Draw the truth table to prove the following proportional logic expression: A <=> B = (A <=> B) ^ (B => A) [3] (b) State a difference between a Tautology and Contradiction. [2] 2 (c) Draw the truth table and a logic gate diagram of Octal to Binary Encoder. [5] Section B Answer two questions Each program should be written in such a way that it clearly depicts the logic of the problem. This can beachieved by using mnemonic names and comments in the program. (Flowcharts and algorithms are notrequired) The programs must be written in Java. Question 7 [10] A class Composite contains a two dimensional array of order [m x n]. The maximum values possible for both ‘m’ and ‘n’ is 20. Design a class Composite to fill the array with the first (m x n) composite numbers in column wise. The details of the members of the class are given below: Class name : Composite Data members /instance variables : arr[ ][ ] : stores the composite numbers column wise m: integer to store the number of rows n: integer to store the number of columns Member functions : Composite(int mm, intnn ) : to initialize the size of the matrix m=mm and n=nn IntisComposite(int p ) : returns 1 if number is composite otherwise returns 0. void fill ( ) : wise to fill the elements of the array with the first (m × n) composite numbers in column void display( ) : displays the array in a matrix form. Specify the class Composite giving details of the constructor Composite (int,int), intisComposite(int), void fill( ) and void display( ). Define a main( ) function to create an object and call the functions accordingly to enable the task. Question8. In “Piglatin” a word such as KING is replaced by INGKAY, while TROUBLE becomes OUBLETRAY and so on. The first vowel of the original word becomes the start of the translation, any preceding letters being shifted towards the end and followed by AY.Words that begin with a vowel or which do not contain any vowel are left unchanged. 3 Design a class Piglatin using the description of the data members and member functions given below: Class name Piglatin variables : Txt to store a word len to store the length Member functions : Piglatin( ) constructor to initialize the data members void readstring( ) to accept the word input in UPPER CASE void convert ( ) converts the word into its piglatin form and displays the word (changed or unchanged) void consonant( ) Counts and displays the number of Consonants present in the given word. Specify the class Piglatin giving the details of the constructor, void readstring( ), void convert( ) and void consonant( ). Also define the main function to create an object and call methods accordingly to enable the task. [10] Question 9. A class Hifact has been defined to find the HCF of two numbers using the recursive technique. This HCF is used to find the LCM of two numbers. Some members of the class are given below:- Class name : Hifact Data members a, b ,hcf, lcm : integers Member functions Hifact() : constructor to assign initial values to data members Voidgetdata() : to input values of a and b void change() : to swap a and b if a> b intrechcf(int, int) : to find hcf using recursive technique intfn_lcm(int,int,int) : to find lcm using a,b and hcf void result() : to invoke rechcf() and fn_lcm() and to print lcm, hcf of the two numbers a and b. 4 Specify the class Hifact giving details of constructor, void getdata(), void change(), intrechcf() and intfn_lcm(). Write the main function and find the hcf and lcm of any two integers a and b. [10] Section C Answer any two questions Each program should be written in such a way that it clearly depicts the logic of the problem step wise.This can also be achieved by using comments in the program and mnemonic names or pseudo codes foralgorithms. The program must be written in Java and the algorithms must be written in general/standard form, wherever required/ specified. (Flowcharts are not required.) Question 10 A class Student defines the personal data of a student while another class Marks defines to the roll number, name of subject and marks obtained by the student. The details of classes are as: Class name: Student Data members/instance variables: name, sex : string variables to store name and gender male/female age : integer variable to store age of the student. Member functions/methods : Student( ) : constructor to assign initial values to the data members. void show( ) : to print personal data of student. Class Name : Marks Data members/instance variables : rollno, marks : integers to store roll number and marks. subject : string variable to store name of subject Member functions/methods : Marks( ) : constructor to assign initial values to the data members of the child and Base class. int point() : to return the point obtained according to the following: Marks Point >=90 1 70 - 89 2 5 50 - 69 3 40 - 49 4 < 40 5 void show( ) : to display name, sex, age, roll number, marks, subject and point of the student by invoking suitable function. Specify the class Student giving the details of the constructor, function void show(). Using the concept of inheritance, specify the class Marks giving the details of the constructor,intpoint() and void show( ) function. You do not need to write the main() function. [5] Question 11. Rack is a kind of data structure which can store utmost 20 books. The Rack restriction is that a book can be kept into the rack or removed only at one end and i.e., on the top. The class Rack has the following details. Class name: Rack Data members book[] : an array of string of maximum 50 locations to store books. limit : stores the capacity of the array name : String variable to store name of the book. top: integer to indicate topmost book in the rack. Member functions Rack():constructor to store blank in the array book[]. Rack(int m) : constructor to initialize the data members m to limit and -1 to top. voidputthebook() : input name of the book into variable name and adds it on the top into the array[],if possibleelse display the message “overflow” voidremovebook() : to remove a book from the top of the rack, if array is empty then display the message “Rack underflow” voiddisp() : displays the books present in the list Specify the class Rack giving details of only the constructor Rack(int), member function voidputthebook(int), voidremovebook().Assume that other functions have been defined.The main function need not be written. [5] 6 Question 12. A magic number is a number in which the eventual sum of digits of the number is equal to 1. For example, 172 = 1 + 7 + 2 = 10 10 = 1 + 0 = 1 Then 172 is a magic number. Design a class Magic to check if a given number is a magic number. Some of the members of the class are given below: Class name : Magic Data members n Member functions Magic() voidgetnum(intnn) intsum_of_digits(int) : stores the number : constructor to assign 0 to n : to assign the parameter value to the number, n=nn : return the sum of the digits of number void ismagic() checks if the given number is a magic number by calling the function sum_of_digits(int) and displays appropriate message. [5] 7 ―――――――――― ISC Class 12 Sample Paper 2 Standard: 12 Subject: Computer Max Marks: 70 Max. Time 3 hours --------------------------------------------------------------------------------------------------------------------------------------------- Answer all questions in Part I (compulsory) and six questions from Part-II, choosing two questions from Section-A, two from Section-B and two from Section-C. All working, including rough work, should be done on the same sheet as the rest of the answer. The intended marks for questions or parts of questions are given in brackets [ ]. ----------------------------------------------------------------------------------------------------------------------------------------- Question 1. PART I Answer all questions [1X5=5] a) Find the dual of: Y·X+X'+1=1 b) Write the maxterm and minterm, when the inputs are A=O, B=1, C=1 and D=O. c) State the difference between an interface and a class. d) What is an abstract class? e) Define inheritance. How is it useful in programming? Question 2. [2 x 5=10] a) Define a Queue. How is dequeue is different from queue b) State the difference between Function Overloading and Function Overriding. c) Convert the following expression F(X,Y,Z)=XY+Y’Z into minterms. d) Convert the following infix expression to postfix form:A+B/C*(D/E*F) e) A matrix A[m][n] is stored with each element requiring 4 bytes of storage. If the base address at A[1][1] is 1500 and the address at A[4][5] is 2520, determine the number of rows of the matrix when the matrix is stored in Column Major Wise. Question3. [5] The following function magicfun( ) is a part of some class. What will the function magicfun() return when the value of n=7 and n=10 respectively? Show the dry run/working: int magicfun( int n) { if ( n= = 0) . return 0; else return magicfun(n/2)* 10 + (n % 2); } Part II Answer six questions in this part, choosing two questions from Section A, two from B and twofrom Section C. Section A Answer any two questions Question 4. a) Given X(A,B,C,D)=Σ (1,2,5,8,9,10) 1. Reduce the above expression by using 4- variable-map(SOP), showing the various groups (octal, quads, pairs) [4] 2. Draw the logic gate diagram of the reduced expression. Assume that the variable and their complements are available as input. [1] b) Given X(A,B,C,D)=π (0,8,10,12,13,14,15) 1. Reduce the above expression by using 4- variable-map(POS), showing the various groups (octal, quads, pairs) [4] 2. Draw the logic gate diagram of the reduced expression. Assume that the variable and their complements are available as input. [1] Question 5 (a)Prove that complement of A.(A+B).B.(B+C’) is a universal gate. [3] (b) Prove the Boolean expression using Boolean laws. Also, mention the law used at each step. F = (x' + z) + [ (y' + z) • (x' + y) ]' = 1 [3] (c) What is a decoder? Draw the logic diagram for a binary to octal (3 to 8) decoder. [4] Question 6 (a) A passenger is allotted a window seat in an aircraft, if he/she satisfies the criteria given below • The passenger is below 10 years and is accompanied by an adult OR • The passenger is a lady and is not accompanied by an adult OR • The passenger is not below 10 years, but is travelling the first time The inputs are A: The passenger is below 10 years C: The passenger is accompanied by an adult. L: The passenger is a lady. F: the passenger is travelling for the first time. (in all cases 1 indicates yes and 0 indicates no) Output: W- Denotes the passenger is allotted a window seat (1 indicates yes and 0 indicates no) Draw the truth table for the inputs and outputs given above and with SOP expression for W(A, C, L, F) [5] (b) Define SOP form of an expression and POS form of an expression. Give an example for each. [3] (c) Given F(x,y,z) =∑ (1,3,7) Verify : F(x,y,z)=π (0,2,4,5,6) if both are equal. [2] Section B Answer two questions Each program should be written in such a way that it clearly depicts the logic of the problem. This can be achieved by using mnemonic names and comments in the program. (Flowcharts and algorithms are not required) The programs must be written in Java. Question 7 [10] A disarium number is a number in which the sum of the digits to the power of their respective position is equal to the number itself. Example: 135 = 11 + 32 + 53 Hence, 135 is a disarium number. Design a class Disarium to check if a given number is a disarium number or not. Some of the members of the class are given below: Class name Disarium Data members/instance variables: int num int size stores the number stores the size of the number Member functions/methods; Disarium(int nn) parameterized constructor to initialize the data members n = nn and size = 0 void countDigit( ) counts the total number of digits and assigns it to size int sumofDigits(int n, int p) returns the sum of the digits of the number(n) to the power· of their respective positions(p) using recursive technique void countDigit( ) Checks whether the numberis a disarium number and displays the result with an appropriate message Specify the class Disarium giving the details of the constructor( ), void countDigit( ), int sumofDigits (int, int) and void check( ). Define the main( ) function to create an object and call the functions accordingly to enable the task. Question8. [10] A class SwapSort has been defined to perform string related operations on a word input. Some of the members of the class are as follows: Class name SwapSort· Data members/instance variables: Wrd to store a word len integer to store length of the word swapwrd sortedword to store the swapped word · to store the sorted word Member functions/methods; SwapSort( ) void readword( ) void sortword() default constructor to initialize data members with legal initial values to accept a word in UPPER CASE sorts the characters of the original word. 'in alphabetical order and· stores it in 'sortwrd' void swapchar( ) to interchange/swap the first and last characters of the word in 'wrd' and stores the new word in 'swapwrd' void display( ) displays the original word, swapped word and the sorted word. Specify the class SwapSort, giving the details of the constructor( ), void readword( ), void swapchar( ), void sortword( ) and void display( ). Define the main( ) function to create an object and call the functions accordingly to enable the task. Question 9. [10] A class Matrix contains a two dimensional integer array of order[m xn].The maximum value possible for both m and n is 25. Design a class Matrix to find the difference of the two matrices. The details of the members of the class are given below: Class name Data members arr[][] : Matrix : stores the matrix element m : integer to store the number of rows n : integer to store the number of columns Memberfunctions: Matrix(int mm,int nn) : to initialize the size of the matrix m=mm and n=nn void fillarray() : to enter the elements of the matrix Matrix SubMat(Matrix A) void display() : subtract the current object from the matrix of parameterized Object(A) and return the resulting object. : display the matrix elements. Specify the class Matrix giving details of the constructor(int, int),void fillarray(),Matrix SubMat(Matrix)and void display(). Define the main()function to create an object and call the functions accordingly to enable the task. Section C Answer any two questions Each program should be written in such a way that it clearly depicts the logic of the problem step wise.This can also be achieved by using comments in the program and mnemonic names or pseudo codes for algorithms. The program must be written in Java and the algorithms must be written in general/standard form, wherever required/ specified. (Flowcharts are not required.) Question 10 [5] A class Personal contains employee details and another class Retire calculates the employee’s Provident Fund and Gratuity. The details of the two classes are given below: Class name Data Members: Name Pan basic_pay acc_no Member functions: Personal( …. ) void display( ) Personal stores the employee name stores the employee PAN number stores the employee basic salary stores the employee bank account number parameterized constructor to assign value to data members to display the employee details Class name Data Members: Yrs Pf Grat Member functions: Retire ( …. ) classes. void provident( ) void gratuity( ) void display1( ) Retire stores the employee years of service stores the employee provident fund amount stores the employee gratuity amount Parameterized constructor to assign value to data members of both the calculates the PF as (2% of the basic pay) * years of service. calculates the gratuity as 12 months salary, if the years of service is more than or equal to 10 years else the gratuity amount is nill. Displays the employee details along with the PF and gratuity amount. Assume that the super class Personal has been defined. Using the concept of inheritance specify the class Retire giving details of the constructor, void provident () and void gratuity ().The super class and themain function need not be written Question 11. [5] A dequeue enables the user to add and remove integers from both the ends i.e. front and rear. Define a class Dequeue with the following details: Class name Data members ele[] cap front rear Memberfunctions Dequeue(int max) void pushfront(int v) :Dequeue : array to hold integer elements. : stores the maximum capacity of the array. : to point the index of the front. : to point the index of the rear. : constructor to initialize the data member cap=max, front=rear=0 and create the integer array. : to add integers from the front index, if possible else display the message(“full from front”). int popfront() : to remove and return element from front. If array is empty then return 999. void pushrear(int v) : to add integers from the front index if possible else display the message(“full from rear”). int poprear() : to remove and return elements from rear. If the array is empty then return999. Specify the class Dequeue giving details only of the constructor(int),void pushfront(int) and int poprear(). Assume that other functions have been defined.The main function need not be written. Question 12. A magic number is a number in which the eventual sum of digits of the number is equal to 1. For example, 172 = 1 + 7 + 2 = 10 10 = 1 + 0 = 1 Then 172 is a magic number. Design a class Magic to check if a given number is a magic number. Some of the members of the class are given below: Class name : Magic Data members n Member functions Magic() void getnum(int nn) int sum_of_digits(int) : stores the number : constructor to assign 0 to n : to assign the parameter value to the number, n=nn : return the sum of the digits of number void ismagic() checks if the given number is a magic number by calling the function sum_of_digits(int) and displays appropriate message. [5] ―――――――――― ISC Class 12 Sample Paper 3 Standard: 12 Subject: Computer Max Marks: 100 Max. Time 3 hours Answer all questions in Part I (compulsory) and seven questions from Part-II, choosing three questions from Section-A, two from Section-B and two from Section-C . All working, including rough work, should be done on the same sheet as the rest of the answer. The intended marks for questions or parts of questions are given in brackets [ ]. PART I Answer all questions. While answering questions in this Part, indicate briefly your working and reasoning, wherever required. Question 1 [1X5=5] (a) State the two distributive laws of Boolean Algebra. Prove any one of them with the help of Truth Table. (b) Draw the truth table to verify the expression : p ⇒ q is equivalent to ∼ q ⇒ ∼ p (∼ q = q = q’) (c) Find the complement of the following: [(xy)′ • x] [ (xy)′ • y] (d) Simplify the following Boolean Expression using laws of Boolean Algebra. At each step, clearly state the law used for simplification. z . ( z + x ). x . ( y + y ) (e) Given F ( x, y, z ) = xz + xy + yz Write the function in canonical sum of products form. Question 2 (a) What do LIFO and FIFO stand for? [2] (b) For an array of real numbers x [6][20], find the address of x [5] [4 ], if x [0] [0] is stored in location 100 in the column major order. Assume that each element requires 4 bytes. [2] (c) State the 2 difference between an constructor and function [2] (d) Convert the following infix expression to its postfix form: [2] b * [ (a / d ) - ( c * ( e - f ) ) ] (e) Define a binary tree. [2] Question 3 Give output of the following function where x and y are arguments greater than 0. Show the dry run/working. int strange (int x, int y) { //Assuming x>0 and y>0 if(x>=y) { x = x-y; return strange(x , y); } else return x; } (i) What will the function strange(20,5) return ? [2] (ii) What will the function strange(15,6) return ? [2] (iii) In one line, state what the function is doing. [1] PART – II Answer seven questions in this part, choosing two questions from Section A, two from Section B and two from Section C. SECTION- A Answer any three questions. Question 4 (a) Given the Boolean function: [5] F ( P, Q, R, S ) = ∑ ( 0, 1, 3, 4, 5, 6, 7, 9, 10, 11, 13, 15 ) Use Karnaugh’s map to reduce the function F, using the SOP form. Draw a logic gate diagram for the reduced SOP form. You may use gates with more than two inputs. Assume that the variable and their complements are available as inputs. (b) Given the Boolean function : [5] X ( P, Q, R, S ) = π ( 3, 8, 10, 12, 13, 14, 15 ) Use Karnaugh’s map to reduce this function X using the given POS form. Draw a logic gate diagram for the reduced POS form. You may use gates with more than two inputs. Assume that the variables and their complements are available as inputs. Question 5 (a) Draw the truth table and logic circuit diagram for a Decimal to Binary Encoder. [5] ∑ (b) Given : F(x, y, z) = (1,3,7) [2] Verify : F(x, y, z) = π (0,2,4,5,6) if both are equal (c) Simplify the following expression by using Boolean laws. Show the working and [3] also mention the laws used : X’Y’Z’ + XYZ’ + XY’Z’ + X’YZ’ Question 6 (a) Define SOP Form of an expression and POS Form of Give an example for each. an expression. [3] (b) Which gate is equivalent to : [3] (NOR) OR (XOR) (c) Define a Half Adder. Draw the Truth Table and Logic diagram of a Half Adder. [4] SECTION – B Answer any two questions. Each program should be written in such a way that it clearly depicts the logic of the problem. This can be achieved by using mnemonic names and comments in the program. (Flowcharts and Algorithms are not required.) The programs must be written in Java. Question 7 A perfect square is an integer which is the square of another integer. For example, 4, 9, [10] 16 .. are perfect squares. Design a Class Perfect with the following description: Perfec Class name :t Data members/instance variables n : stores an integer number Member functions: Perfect( ) : default constructor Perfect(int) : parameterized constructor to assign a value to ‘n’ void perfect_sq() : to display the first 5 perfect squares larger than ‘n’ (if n = 15, the next 3 perfect squares are 16, 25, 36) void sum_of() : to display all combinations of consecutive integers whose sum is equal to n. ( the number n = 15 can be expressed as 1 2 34 5 4 56 78 Specify the class Perfect giving details of the constructors, void perfect_sq( ) and void sum_of(). Also define the main function to create an object and call methods accordingly to enable the task. Question 8 A class RecFact defines a recursive function to find the factorial of a number. The [10] details of the class are given below: Class name Data members/instance variables n r Member functions RecFact( ) void readnum( ) int factorial(int) Void factseries( ) : RecFact : stores the number whose factorial is required. : stores an integer : default constructor : to enter values for ‘n’ and ‘r’ : returns the factorial of the number using the Recursive Technique. : to calculate and display the value of n!+(r-2)! ( n − r)! Specify the class RecFact giving the details of the constructor and member functions void readnum( ), int factorial(int) and void factseries( ). Also define the main function to create an object and call methods accordingly to enable the task. Question 9 In “Piglatin” a word such as KING is replaced by INGKAY , while TROUBLE [10] becomes OUBLETRAY and so on . The first vowel of the original word becomes the start of the translation, any preceding letters being shifted towards the end and followed by AY. Words that begin with a vowel or which do not contain any vowel are left unchanged. Design a class Piglatin using the description of the data members and member functions given below: Class name : Piglatin Data members /instance variables : Txt : to store a word len : to store the length Member functions : Piglatin( ) void readstring( ) void convert ( ) void consonant( ) : constructor to initialize the data mrmbers : to accept the word input in UPPER CASE : converts the word into its piglatin form and displays the word (changed or unchanged) : counts and displays the number of Consonents present in the given word. Specify the class Piglatin giving the details of the constructor, void readstring( ), void convert( ) and void consonant( ). Also define the main function to create an object and call methods accordingly to enable the task. SECTION – C Answer any two questions. Each program should be written in such a way that it clearly depicts the logic of the problem stepwise. This can be achieved by using comments in the program and mnemonic names or pseudo codes for algorithms. The programs must be written in Java and the algorithms must be written in general / standard form, wherever required / specified. (Flowcharts are not required.) Question 10 A class Author contains details of the author and another class Book List contains [5] details of the books written by him. The details of the two classes are given below: Class name : Author Data members authorno name Member functions : stores the author’s number : stores the author’s name Author ( ) Author ( … ) void show( ) : default constructor : parameterised constructor to assign values to author number and name : to display the author’s details 7 Class name : Booklist Data members/instance variables bookno bookname price edition Member functions : Long type variable to the store book number : stores the book name : float variable to store the price : integer type variable to store the edition number Booklist (…) : parameterized constructor to assign values to data members of both the classes void show( ) : to display all the details Specify the class Author giving details of the constructors and member function void show( ). Using the concept of Inheritance, specify the class Booklist giving details of the constructor and the member function void show( ). Also define the main function to create an object and call methods accordingly to enable the task. Question 11 In a computer game, a vertical column and a pile of rings are displayed. The objective [5] of the game is to pile up rings on the column till it is full. It can hold 10 rings at the most. Once the column is full, the rings have to be removed from the top till the column is empty and then the game is over. Define the class RingGame with the following details: Class name : RingGame Data members/instance variables ring [ ] : array to hold rings (integer) max : integer to hold maximum capacity of … (see the PDF for the full paper)