Computer Applications Past Paper PDF

Computer Applications Solution (ICSE) X  Chapter 1 Revision Tour I Mental Drill A. Tick () the correct option. 1. Name the programming technique that implements programs as an organised collection of...

Computer Applications Solution (ICSE) X  Chapter 1 Revision Tour I Mental Drill A. Tick () the correct option. 1. Name the programming technique that implements programs as an organised collection of interactive objects. a. Procedure Oriented Programming b. Modular Programming c. Object Oriented Programming d. None of these Ans. c. Object Oriented Programming 2. Name the characteristics of Object Oriented Programming that hides the complexity and provides a simple interface. a. Encapsulation b. Polymorphism c. Abstraction d. Inheritance Ans. c. Abstraction 3. Which among the following operator is used to access individual members of an object? a.. (dot) b. + (plus) c. – (minus) d. / (divide) Ans. a.. (dot) 4. Which among the following modifier is used in a ‘class’? a. public b. default c. Both a and b d. None of these Ans. c. Both a and b 5. Which among the following is a valid class name? a. Simple Interest b. SimpleInterest c. 1SimpleInterest d. Simple@Interest Ans. b. SimpleInterest 6. Which among the following is a valid object name? a. obj1 b. 1obj c. Obj 1 d. Obj#1 Ans. a. obj1 Computer Applications – X (ICSE Course) Answers 2  7. Which among the following is a valid float literal? a. 12.36f b. 12.36F c. 12.36 d. Both a and b Ans. d. Both a and b 8. Which among the following is a valid octal integer literal? a. 0178 b. 675 c. 0675 d. 0X675 Ans. c. 0675 9. Which among the following is a valid method of initialising? a. boolean f=true; b. boolean f=True; c. boolean f=’true’; d. None of these Ans. a. boolean f=true; 10. Which among the following is not a punctuator? a. ; semicolon b. , comma c. : colon d.. dot Ans. d.. dot 11. Which among the following is not a primitive data type? a. int b. float c. String d. char Ans. c. String 12. What is the largest possible value that can be stored in short data type? a. 215-1 b. 231-1 c. 27-1 d. 263-1 Ans. a. 215-1 13. If a is of type int and b is of type float what would be the resultant data type of a+b? a. int b. float c. double d. short Ans. b. float B. State whether the following statements are True (T) or False (F). 1. Encapsulation refers to the art of hiding the complexities and giving a simple interface. F 2. Procedure Oriented Language follows top down approach. T 3. Java is an example of Object Oriented Language. T 3 Revision Tour I  4. Hiding the complexity and giving a simple interface is called Inheritance. F 5. Abstraction is same as encapsulation. F 6. An object is called a class factory. F 7. A class is an instance of an object. F 8. A class is a mechanism to implement encapsulation. T 9. Data members in a class is used to represent the characteristic of an object. T 10. The new operator is used to create an object. T 11. It’s a rule to have a class-name beginning in capital letter. F C. Fill in the blanks. 1. A class is a template that binds together data and methods together. 2. The values in the attributes of an object is called the state of an object. 3. The dot operator is used to access the individual members of a class. 4. The keyword new is used to allocate memory space for an object. 5. The default and public access modifier is used with a class. 6. An object is an identity with certain characteristic and behaviour. 7. The values/attributes of the characteristics of an object are called the state of an object. 8. All the complexities of a program should be encapsulated in such a way so that abstraction is obtained. 9. Inheritance allows us to encompass the parent class’ state and behaviours into its child.. 10. Poly-means many and Morphism means forms. Section A Answer the following questions: 1. How are objects implemented in software? Ans. In a software the characteristics of an object are represented through data members and behaviour is represented through member functions. 2. What is abstraction? How is encapsulation related to it? Ans. Abstraction is a principle of Object Oriented Programming (OOP) that hide certain details and only show the essential features of the object. 3. Define Encapsulation. Ans. Encapsulation is a principle of Object Oriented Programming (OOP) that binds together characteristics and behaviour of an object into a single unit represented by a class. Computer Applications – X (ICSE Course) Answers 4  4. What is Inheritance? Ans. Inheritance is the concept that when a class of objects is defined, any subclass that is defined can inherit the definitions of one or more general classes. 5. What is Object Oriented Programming? Ans. Object Oriented Programming (or OOP) is a technique of implementing programs which are organized as a co-interactive collection of objects, each of which represents an instance of a class. 6. State three differences between Procedure Oriented Language and Object Oriented Languages. Ans. Procedure Oriented Programming Object Oriented Programming A large program is divided into smaller A program is represented as an object. segments or procedures. More importance is given to the program More importance is given to the data rather rather than the data. than the program. It follows top down approach. It follows bottom up approach. 7. State the four characteristics/principles of Object Oriented Programming. Ans. Encapsulation, Abstraction, Polymorphism and Inheritance. 8. What are keywords? Give an example. Ans. A keyword is a reserved word that has a special significance to the compiler and cannot be used anywhere else other than what it is intended for. Example- for, if, else, while etc. 9. What are identifiers? Ans. Identifiers are the names of variables, methods, classes, packages and interfaces. 10. What is a literal? Ans. Literal is a constant value that can be assigned to a variable. 11. Why is an object called an instance of a class? Ans. An object is called an instance of a class as every object created from a class gets its own instances of the variables defined in the class. Multiple objects can be created from the same class. 12. Write one difference between primitive data type and composite data type. Ans. Fundamental data type Composite data type These are inbuilt data type provided by the These are data types created by the user using Java Language. fundamental or user defined data type or both. 5 Revision Tour I  The size of it is fixed. The size of different user-defined data type depends upon the size of the individual components of it. These data types are available in all parts of These data types are available only as specified a program within a class. by the access specifiers. 13. Give one example each of primitive data type and composite data type. Ans. Primitive data type: int, short, boolean, char etc. Composite data type: class, arrays, interface etc. 14. State two differences between a class and an object. Ans. Object Class Class is a blueprint or template from which Object is an instance of a class. objects are created. Object is a real world entity such as pen, laptop, Class is a group of similar objects. mobile, bed, keyboard, mouse, chair etc. Object is a physical entity. Class is a logical entity. Object is created through new keyword mainly Class is declared using class keyword e.g. e.g. Student s1=new Student(); class Student{} Object is created many times as per Class is declared once. requirement. Class doesn’t allocated memory when it is Object allocates memory when it is created. created. 15. Give one point of difference between unary and binary operators. Ans. Unary operator works on a single operand and Binary operator works on 2 operands. 16. What do you understand by type conversion? Ans. Type conversion is the process of converting one Primitive data type to another primitive data type. It may be done either implicitly or explicitly. 17. State the difference between a Boolean literal and a character literal. Ans. A boolean literal consist of only two values i.e. true or false. A character literal on the other hand is any character enclosed within single quotes. 18. Identify the literals as given below: i. 0.5 ii. ‘A’ iii. false iv. “a” Ans. i. double ii. char iii. boolean iv. String Computer Applications – X (ICSE Course) Answers 6  19. Which two access specifier is used in a class declaration? Ans. public and default 20. Why is a class called an object factory? Ans. A class is called an object factory because objects are created from a class. An object is an instance of a class. 21. Evaluate the value of n if the value of p=5 and q=19: int n = (q-p)>(p-q)?(q-p):(p-q); Ans. n=14 22. What is meant by precedence of operators? Ans. When several operations occur in an expression, each part is evaluated and resolved in a predetermined order called operator precedence. 23. What is Operator Associativity? Ans. Operator associativity of an operator is a property that determines how operators of the same precedence are grouped in the absence of parentheses; i.e. in what order each operator is evaluated when two operators of same precedence appear in an expression. 24. State the difference between an accumulator and counter. Ans. Accumulator is a variable that is used to add or accumulate a list of items. Counter on the other hand is a variable, which is used to keep track of the number of times an operation is being performed. 25. What does a class encapsulate? Ans. A class encapsulates characteristics represented by data member and behaviour represented by member methods. 26. State the Java concept that is implemented through: i. A super class and a sub-class. ii. The act of representing essential features without including background details. Ans. i. Inheritance ii. Abstraction 27. Write a statement in Java that will declare an object named si of the SimpleInterest class. Ans. SimpleInterest si = new SimpleInterest(); 28.Rewrite the following program after removing the errors, underlining each correction: class My Class { int a, b; void initialize( ) { 7 Revision Tour I  a=5; b=6; } void show ( ) { System.out.println (a+ ‘’ ‘’ + b); } static void main( ) { My Class ob = new My Class ( ); ob. initialize ( ); show ( ). ob; } } Ans. class MyClass { int a, b; void initialize( ) { a=5; b=6; } void show ( ) { System.out.println (a+ ‘’ ‘’ + b); } static void main( ) { MyClass ob = new MyClass( ); ob. initialize( ); ob.show ( ); } } 29. Which among the following are invalid class names in Java? State with reasons. i. Compound Interest ii. 1MyClass iii. MyClass$ iv. Myclass# v. My@Class Ans. i. Invalid, as a variable name cannot have a blank space. ii. Invalid, as a variable name cannot begin with a digit. iv. Invalid, as a variable name cannot have a special character, like #. v. Invalid, as a variable name cannot have a special character, like @. Computer Applications – X (ICSE Course) Answers 8  30. What is the resultant data type of the following mathematical expression? a+b*c-d a. where a is int, b is int, c is float and d is float type b. where a is float, b is long, c and d is of int type c. where a is of double and b,c and d are of int type d. where a is char and b,c and d are of int type e. where a, b, c and d are of int type, however the expression is slightly modified as (a+b*c-d)/7.0 Ans. a. float b. float c. double d int e. double 31. What will be the output of the following programs? 9 Revision Tour I  Ans. a. 5 15 b. 19 -37 c. 6 4 d. 14 14 27 16 15 35 e. true true 10 14 f. true true 8 g. false true h. 10 17 17 true 32. What will be the output when the following code segment is executed? System.out.println(“The king said \”Begin at the beginning!\ “to me”); Ans. The king said “Begin at the beginning!” to me 33. System.out.print(“BEST “); System.out.println(“OF LUCK”); Choose the correct option for the output of the above statements: i. BEST OF LUCK ii. BEST OF LUCK Ans. i. BEST OF LUCK 34. What is the value of y after evaluating the expression given below? y+=++y + y-- + --y; when int y=8 Ans. y=33 Computer Applications – X (ICSE Course) Answers 10  35. Give the output of the following expression: a+=a++ + ++a + --a + a--; when a=7. Ans. a=39 36. If int y=10 then find: int z=(++y * (y++ +5)); Ans. y=12 z=176 37. What are the values of x and y when the following statements are executed? int a = 63, b = 36; boolean x = (a < b ) ? true : false; int y= (a > b ) ? a : b; Ans. x=false y=63 38. What will be the result stored in x after evaluating the following expression? int x=4; x += (x++) + (++x) + x; Ans. x=20 39. What will be the output of the following code? int k = 5, j = 9; k += k++ – ++j + k; System.out.println(“k=” +k); System.out.println(“j=” +j); Ans. k= 6 j= 10 40. What is the result stored in x, after evaluating the following expression? int x = 5; x = x++ * 2 + 3 * –x; Ans. x=-8 41. Write the output of the following: System.out.println(“Incredible”+“\n”+“world”); Ans. Incredible World 42. Name the operators listed below: i. < ii. ++ iii. && iv. ?: 11 Revision Tour I  Ans. i. Relational Operator ii. Unary Operator (Increment) iii. Logical operator (and) iv. Ternary operator 43. State the number of bytes occupied by char and int data types. Ans. char = 2 bytes int = 4 bytes 44. Write one difference between / and % operator. Ans. / is used to find the quotient and % is used to find the remainder, when 2 numbers are divided. 45. Name the primitive data type in Java that is: i. a 64 bit integer and is used when you need a range of values wider than those provided by int. ii. a single 16-bit Unicode character whose default value is ‘\u0000’. Ans. i. long ii. char SECTION B Programming Questions 1. Write a program to find the sum and difference between 25 and 16 using variables in different lines. Ans. class q1 { static void main() { int a=25,b=16,s,d; s=a+b; d=a-b; System.out.println(“Sum=”+s); System.out.println(“Difference=”+d); } } 2. Write a program to find the product of 5, 7 and 12 using variables. Ans. class q2 { static void main() { Computer Applications – X (ICSE Course) Answers 12  int a=5,b=7,c=12,d; d=a*b*c; System.out.println(“Product=”+d); } } 3. Write a program to find the product of the sum and difference between 17 and 2 using variables. Ans. class q3 { static void main() { int a=17,b=2,s,d; s=a+b; d=a-b; System.out.println(“Sum=”+s); System.out.println(“Difference=”+d); } } 4. Write a program to average of 36, 45 and 53 using variables of adequate data type. Ans. class q4 { static void main() { int a=36,b=45,c=53; float av; av=(float)(a+b+c)/3; System.out.println(“Average=”+av); } } 5. Write a program using int variables to find the sum of three numbers say 15, 36 and 45 and subtract the result from 100 using variables. Ans. class q5 { static void main() { int a=15,b=36,c=45,d=100,e; e=d-(a+b+c); System.out.println(“Answer=”+e); } } 13 Revision Tour I  6. Write a program to display the names of five fruits with a single System.out.println(); statement, but in different lines. Ans. class q6 { static void main() { System.out.println(“Apple\nOrange\nGuava\nBanana\nLemon”); } } 7. Write a program to find the sum, difference and product of 12.35 and 7.3 using variables with a single System.out.println(); statement, however with horizontal tab space in the result. Ans. class q7 { static void main() { float a=12.35f,b=7.3f,s,d,p; s=a+b; d=a-b; p=a*b; System.out.println(“Sum=”+s); System.out.println(“Difference=”+d); System.out.println(“Product=”+p); } } 8. Write a program using float type variables to find the area and perimeter of a square whose side is 12.5 cm. Ans. class q8 { static void main() { float s=12.5f,a,p; a=s*s; p=4*s; System.out.println(“Area=”+a); System.out.println(“Perimeter=”+p); } } 9. Write a program using int variables to find the area and perimeter of a rectangle of length 12cm and breadth 8cm. Ans. class q9 { static void main() Computer Applications – X (ICSE Course) Answers 14  { int l=12,b=8,a,p; a=l*b; p=2*(l+b); System.out.println(“Area=”+a); System.out.println(“Perimeter=”+p); } } 10. Write a program using variables to find the profit and profit percent of a certain transaction where S.P.= `10000 and C.P.= ` 7000. Ans. class q10 { static void main() { float sp=10000,cp=7000,p,pp; p=sp-cp; pp=p/cp*100; System.out.println(“Profit=”+p); System.out.println(“Profit Percent=”+pp); } } 11. Write a program to input the Principal, Rate and Time and calculate the Simple Interest. Ans. import java.util.*; class q11 { static void main() { Scanner sc=new Scanner(System.in); float p,r,t,si; System.out.println(“Enter the principal, rate and time:”); p=sc.nextFloat(); r=sc.nextFloat(); t=sc.nextFloat(); si=(p*r*t)/100; System.out.println(“Simple Interest=”+si); } } 15 Revision Tour I  12. Write a program using variables to find the area and circumference of a circle whose radius is 12cm. Note that : Area of a circle= π r2 Circumference of a circle = 2 π r where r is the radius of the circle and π is 3.142. Ans. class q12 { static void main() { float r=12,a,pie=3.142f,c; a=pie*r*r; c=2*pie*r; System.out.println(“Area=”+a); System.out.println(“Circumference=”+c); } } 13. Write a program to initialise two integer variables a and with 5 and 6 respectively and interchange them. Thus after interchanging, a and b will be 6 and 5 respectively. Ans. class q13 { static void main() { int a=5,b=6,c; System.out.println(“Before Interchange: a=”+a+“b=”+b); c=a; a=b; b=c; System.out.println(“After Interchange: a=”+a+“b=”+b); } } 14. Write a program to initialise three int variables a, b and c with 234, 456 and 712 and store the sum of the last digits of the variables into d and display it. Ans. class q14 { static void main() { int a=234,b=456,c=712,d; d=a%10+b%10+c%10; System.out.println(“Sum=”+d); Computer Applications – X (ICSE Course) Answers 16  } } 15. Write a program to initialise an int variable a with 76498 and from it extract the first digit and store it into a variable f and extract the last digit into a variable l and display both these digits. Ans. class q15 { static void main() { int a=76498,f,l; f=a/10000; l=a%10; System.out.println(“First Digit=”+f); System.out.println(“Last Digit=”+l); } } 16. Write a program using ternary operator to check whether 27 is a multiple of 3 or not. Ans. class q16 { static void main() { System.out.println((27%3==0)?“Multiple of 3”:“Not a multiple of 3”); } } 17 Revision Tour I  Chapter 2 Revision Tour II Mental Drill A. Tick () the correct option. 1. Which among the following is not a valid error in Java? a. Syntax errors b. Logical errors c. Run-time errors d. Technical errors Ans. d. Technical errors 2. Which among the following Scanner methods allows us to input a number with a decimal point? a. nextInt() b. nextFloat() c. nextDecimal() d. nextPoint() Ans. b. nextFloat() 3. The output in BlueJ occurs in which window? a. Console window b. Terminal window c. Both a and b d. None of these Ans. b. Terminal window 4. The input in BlueJ occurs in which window? a. Console window b. Terminal window c. Both a and b d. None of these Ans. b. Terminal window 5. Assigning value to a variable during declaration is called. a. Declaration b. Assignment c. Initialisation d. None of these Ans. c. Initialisation 6. Which among the following is used to represent single-line comment? a. // b. /* c. \\ d. the loop executes once. y=y/x =1/1=1 x the loop executes next time The entire process will continue infinite number of times, with the output as 1 in different lines. 25. Give the output of the following code fragment: when (i) opn = ‘b’ (ii) opn = ‘x’ (iii) opn = ‘a’ switch (opn) { case ‘a’: System.out.println(“Platform Independent”); break; case ‘b’: System.out.println(“Object Oreinted”); case ‘c’: Computer Applications – X (ICSE Course) Answers 24  System.out.println(“Robust and Secure”); default: System.out.println(“Wrong Input”); } Ans. i. Object Oreinted Robust and Secure Wrong Input ii. Wrong Input iii. Platform Independent 26. Convert the following if else if construct into switch case if( var==1) System.out.println(“good”); else if(var==2) System.out.println(“better”); else if(var==3) System.out.println(“best”); else System.out.println(“invalid”); Ans. switch(var) { case 1: System.out.println(“good”); break; case 2: System.out.println(“better”); break; case 3: System.out.println(“best”); break; default: System.out.println(“invalid”); } 27. Rewrite the following using ternary operator: if (bill >10000 ) discount = bill * 10.0/100; else discount = bill * 5.0/100; Ans. discount=(bill >10000 ) ? bill * 10.0/100: bill * 5.0/100; 25 Revision Tour II  28. Rewrite the following program segment using the if.. else statement. comm = (sale>15000)?sale*5/100:0; Ans. if (sale>15000) comm=sale*5/100 else comm=0; 29. Rewrite the following using ternary operator : if(x%2==0) System.out.print(“EVEN”); else System.out.print(“ODD”); Ans. System.out.print((x%2==0)?”EVEN”:“ODD”); 30. Convert the following segment into an equivalent do loop. int x,c; for (x=10, c=20; c>=10; c = c – 2) x++; Ans. int x=10,c=20; do { x++; c=c-2; }while(c>=10); 31. Give the output of the following program segment and also mention how many times the loop is executed: int i; for (i = 5 : i > 10; i ++) System.out.println(i); System.out.println(i * 4); Ans. Output: 20 The loop do not execute, as the condition results to false. 32. Convert the following while loop to the corresponding for loop: int m = 5, n = 10; while (n>=1) { System.out.println(m*n); n–; } Computer Applications – X (ICSE Course) Answers 26  Ans. int m=5,n; for(n=10;n>=1;n--) { System.out.println(m*n); } 33. Convert following do-while loop into for loop. int i = 1; int d=5; do { d=d*2; System.out.println(d;) i++ ; } while (i