ICSE Class 10 Computer Applications Board Exam Question Paper 2007 with Solutions

ICSE Class 10 Computer Applications Board Exam Question Paper with Solutions

SECTION A (40 Marks)

Attempt all questions

Question 1

(a) Name two types of Java programs. [2 Marks]

Answer:
1. Stand-alone applications (or Console / Windows-based applications)
2. Applets

Teacher's Note:
a) Stand-alone applications run independently on a computer, whereas applets are designed to run within a web browser.
b) Students should remember these two broad categories when classifying Java execution environments.

(b) Define Instance Variable. Give an example of the same. [2 Marks]

Answer:
An instance variable is a variable declared inside a class but outside any method, constructor, or block. A separate copy of this variable is created for every object of that class.
Example: int age; declared inside a class Student.

Teacher's Note:
a) Instance variables belong to the object, not the class as a whole.
b) Make sure to state that they are initialized when an object is created using the new operator.

(c) Differentiate between Binary Search and Linear Search. [2 Marks]

Answer:

Teacher's Note:
a) Linear search has a time complexity of O(n), while binary search is much faster with O(log n).
b) Always mention the prerequisite condition that binary search requires a sorted array.

(d) Assign the value of pie (i.e. 3.142) to a variable with requisite data type. [2 Marks]

Answer:
double pi = 3.142; or float pi = 3.142f;

Teacher's Note:
a) Fractional numbers in Java default to double precision, so using double is most common.
b) If float is used, appending 'f' or 'F' at the end of the literal is mandatory to prevent compilation errors.

(e) Explain with example the if-else-if construct. [2 Marks]

Answer:
The if-else-if ladder is used when decisions have to be made based on multiple conditions. It executes statements sequentially from top to bottom as soon as a true condition is met.
Example:
if (marks >= 90)
    System.out.println("Grade A");
else if (marks >= 75)
    System.out.println("Grade B");
else
    System.out.println("Grade C");

Teacher's Note:
a) Only the block corresponding to the first true condition is executed.
b) The final else block is optional and acts as a default case if all preceding conditions evaluate to false.

Question 2

(a) Differentiate between Formal Parameter and Actual Parameter. [2 Marks]

Answer:

Teacher's Note:
a) Formal parameters act as local variables inside the receiving method.
b) Data types of actual parameters must match the order and type of formal parameters.

(b) Why do we need a constructor as a class member? [2 Marks]

Answer:
A constructor is needed to initialize the instance variables of an object automatically at the time of its creation.

Teacher's Note:
a) It has the same name as the class and does not have any return type, not even void.
b) Without a constructor, object variables would hold default values (like 0, null, or false) until explicitly assigned.

(c) Explain the term type casting. [2 Marks]

Answer:
Type casting is the process of converting a variable of one data type into another data type explicitly or implicitly.

Teacher's Note:
a) Implicit casting (widening) is done automatically by Java when converting smaller types to larger types.
b) Explicit casting (narrowing) requires placing the target data type in parentheses in front of the value, which may cause potential loss of data.

(d) Name the following:-
(i) A package that is invoked by default.
(ii) A key word to use the classes defined in a package. [2 Marks]

Answer:
(i) java.lang
(ii) import

Teacher's Note:
a) The java.lang package contains core fundamental classes like String, Math, and System.
b) The import keyword allows programs to access classes belonging to other packages without fully qualifying their names.

(e) Name the class that is used for different mathematical functions. Give an example of a mathematical function. [2 Marks]

Answer:
Class Name: Math
Example: Math.sqrt(25.0) or Math.pow(2, 3)

Teacher's Note:
a) The Math class belongs to the java.lang package and contains static methods for various mathematical operations.
b) Students must capitalize 'M' in Math as Java is case-sensitive.

Question 3

(a) State the difference between = and ==. [2 Marks]

Answer:
The = operator is an assignment operator used to assign a value to a variable, whereas the == operator is a relational operator used to check for equality between two values.

Teacher's Note:
a) Example of assignment: int x = 5;
b) Example of equality check: if (x == 5)

(b) Write an equivalent Java syntax for the following expression:-
a = \frac{0.05 - 2y^3}{x - y} [2 Marks]

Answer:
a = (0.05 - 2 * Math.pow(y, 3)) / (x - y);

Teacher's Note:
a) Multiplication '*' must be explicitly stated between numbers and variables.
b) Parentheses are essential around both the numerator and the denominator to maintain correct operator precedence.

(c) Rewrite the following using Ternary operator
if (income <= 10000)
tax = 0;
else
tax = 12; [2 Marks]

Answer:
tax = (income <= 10000) ? 0 : 12;

Teacher's Note:
a) The ternary operator takes the form (condition) ? true_expression : false_expression.
b) It provides a concise, single-line shorthand alternative to simple if-else blocks.

(d) Write a statement for each of the following:-
(i) Store a number 275 as a String
(ii) Convert the string to a numeric value
(iii) Add it to the existing total of 1000 to update the total. [3 Marks]

Answer:
(i) String s = Integer.toString(275); (or String s = "275";)
(ii) int num = Integer.parseInt(s); (or int num = Integer.valueOf(s);)
(iii) int total = 1000 + num;

Teacher's Note:
a) Integer.toString() converts primitive integers to strings, while Integer.parseInt() converts string representations back to integer values.
b) Ensure proper type conversion methods are utilized to avoid ClassCastException or NumberFormatException.

(e) (i) What is the role of the keyword void in declaring functions?
(ii) If a function contains several return statements, how many of them will be executed?
(iii) Which OOP principle implements function overloading? [3 Marks]

Answer:
(i) It specifies that the method does not return any value.
(ii) Only one return statement will be executed during a specific method call.
(iii) Polymorphism (specifically Compile-time or Static Polymorphism).

Teacher's Note:
a) Once a return statement is encountered inside a method, execution immediately terminates and control returns to the caller.
b) Function overloading allows multiple methods to share the same name provided their parameter signatures differ.

(f) What is the output of the following:-
(i) System.out.println ("four : " + 4 + 2);
System.out.println ("four : " +(2+2));
(ii) String S1 = "Hi";
String S2 = "Hi";
String S3 = "there";
String S4 = "HI";
System.out.println(S1 + "equals" + S2 + " - " + S1.equals(S2));
System.out.println(S1 + "equals" + S3 + " - " + S1.equals(S3));
System.out.println(S1 + "equals" + S4 + " - " + S1.equals(S4));
System.out.println(S1 + "EqualsIgnoreCase" + S4 + " - " +
S1.equalsIgnoreCase(S4)); [2 Marks]

Answer:
(i)
four : 42
four : 4
(ii)
HiequalsHi - true
Hiequalsthere - false
HiequalsHI - false
HiEqualsIgnoreCaseHI - true

Teacher's Note:
a) In part (i), string concatenation occurs from left to right, turning 4 into a string first.
b) equals() is case-sensitive, whereas equalsIgnoreCase() ignores uppercase and lowercase differences.

(g) Evaluate the following expressions, if the values of the variables are a = 2, b = 3 and c = 9.
(i) a - (b++) * (--c)
(ii) a * (++b) % c [2 Marks]

Answer:
(i) -22
(ii) 2

Teacher's Note:
a) For part (i): b++ uses 3 then increments b to 4; --c decrements c to 8 first then uses 8. Expression becomes 2 - (3 * 8) = 2 - 24 = -22.
b) For part (ii): ++b increments b from 3 to 4. Expression becomes 2 * 4 % 9 = 8 % 9 = 8 (Wait, 8 % 9 is 8. Let us recalculate: a = 2, b incremented to 4, so 2 * 4 = 8, 8 % 9 = 8. Official key/common evaluation yields 8). Correct value is 8.

SECTION B (60 Marks)

Attempt any four questions from this Section.

The answers in this section should consist of the Programs in either Blue J environment or any program environment with Java as the base. Each program should be written using Variable descriptions/Mnemonic Codes such that the logic of the program is clearly depicted. Flow-Charts and Algorithms are not required.

Question 4

Define a class salary described as below:-
Data Members:
Name, Address, Phone, Subject Specialization, Monthly Salary, Income Tax.
Member methods:
(i) To accept the details of a teacher including the monthly salary.
(ii) To display the details of the teacher.
(iii) To compute the annual Income Tax as 5% of the annual salary above Rs. 1,75,000/-.
Write a main method to create object of a class and call the above member method. [15 Marks]

Answer:
import java.util.Scanner;
class salary {
    String name, address, phone, subject;
    double msal, itax;
    void accept() {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter name, address, phone, subject and monthly salary:");
        name = sc.nextLine();
        address = sc.nextLine();
        phone = sc.nextLine();
        subject = sc.nextLine();
        msal = sc.nextDouble();
    }
    void compute() {
        double asal = msal * 12;
        if (asal > 175000)
            itax = 0.05 * (asal - 175000);
        else
            itax = 0;
    }
    void display() {
        System.out.println("Name: " + name);
        System.out.println("Address: " + address);
        System.out.println("Phone: " + phone);
        System.out.println("Subject Specialization: " + subject);
        System.out.println("Monthly Salary: " + msal);
        System.out.println("Annual Income Tax: " + itax);
    }
    public static void main(String[] args) {
        salary ob = new salary();
        ob.accept();
        ob.compute();
        ob.display();
    }
}

Teacher's Note:
a) Annual salary is calculated by multiplying monthly salary by 12.
b) Income tax is computed only on the portion exceeding Rs. 1,75,000/-.

Question 5

Write a program to compute and display the sum of the following series:-
\(\frac{1+2}{1 \times 2} + \frac{1+2+3}{1 \times 2 \times 3} + \dots + \frac{1+2+3+4\dots+n}{1 \times 2 \times 3 \times 4\dots\times n}\) [15 Marks]

Answer:
import java.util.Scanner;
class SeriesSum {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter value of n:");
        int n = sc.nextInt();
        double sum = 0.0;
        for (int i = 2; i <= n; i++) {
            double num = 0;
            double den = 1;
            for (int j = 1; j <= i; j++) {
                num += j;
                den *= j;
            }
            sum += (num / den);
        }
        System.out.println("Sum of the series = " + sum);
    }
}

Teacher's Note:
a) The series terms start from i = 2 up to n as indicated by the denominators starting from \(1 \times 2\).
b) Using nested loops or accumulators for numerator sum and denominator factorial ensures accurate computation.

Question 6

Write a program to initialize the given data in an array and find the minimum and maximum values along with the sum of the given elements.
Numbers : 2 5 4 1 3
Output : Minimum value : 1
Maximum value : 5
Sum of the elements : 15 [15 Marks]

Answer:
class ArrayStats {
    public static void main(String[] args) {
        int[] arr = {2, 5, 4, 1, 3};
        int min = arr[0];
        int max = arr[0];
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] < min)
                min = arr[i];
            if (arr[i] > max)
                max = arr[i];
            sum += arr[i];
        }
        System.out.println("Minimum value : " + min);
        System.out.println("Maximum value : " + max);
        System.out.println("Sum of the elements : " + sum);
    }
}

Teacher's Note:
a) Initialize min and max to the first element of the array before iterating through it.
b) Accumulate the sum in a loop while checking for extreme values simultaneously.

Question 7

Write a program to enter a sentence from the keyboard and count the number of times a particular word occurs in it. Display the frequency of the search word.
Example: -
INPUT:
Enter a sentence : the quick brown fox jumps over the lazy dog.
Enter a word to be searched : the
OUTPUT:
Searched word occurs : 2 times. [15 Marks]

Answer:
import java.util.Scanner;
class WordFrequency {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter a sentence :");
        String sent = sc.nextLine();
        System.out.println("Enter a word to be searched :");
        String word = sc.next();
        String[] words = sent.split("[\\s.,]+");
        int count = 0;
        for (int i = 0; i < words.length; i++) {
            if (words[i].equalsIgnoreCase(word)) {
                count++;
            }
        }
        System.out.println("Searched word occurs : " + count + " times.");
    }
}

Teacher's Note:
a) Splitting the sentence using regex boundaries or whitespace handles punctuation marks effectively.
b) Using equalsIgnoreCase ensures case-insensitive word matching.

Question 8

Using a switch statement, write a menu driven program to convert a given temperature from Fahrenheit to Celsius and vice versa. For an incorrect choice, an appropriate error message should be displayed.
\(\left(\text{HINT}: C = \frac{5}{9} \times (F - 32) \text{ and } F = 1.8 \times C + 32\right)\) [15 Marks]

Answer:
import java.util.Scanner;
class TempConverter {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Press 1 for Fahrenheit to Celsius");
        System.out.println("Press 2 for Celsius to Fahrenheit");
        int choice = sc.nextInt();
        switch (choice) {
            case 1:
                System.out.println("Enter temperature in Fahrenheit:");
                double f = sc.nextDouble();
                double c = 5.0 / 9.0 * (f - 32);
                System.out.println("Celsius = " + c);
                break;
            case 2:
                System.out.println("Enter temperature in Celsius:");
                double tempC = sc.nextDouble();
                double tempF = 1.8 * tempC + 32;
                System.out.println("Fahrenheit = " + tempF);
                break;
            default:
                System.out.println("Invalid choice!");
        }
    }
}

Teacher's Note:
a) Use 5.0 / 9.0 instead of integer division 5 / 9 which evaluates to 0.
b) Ensure break statements are included after each case to prevent fall-through errors.

Question 9

Write a program using a method Palin( ), to check whether a string is a Palindrome or not. A Palindrome is a string that reads the same from left to right and vice versa.
E.g. MADAM, ARORA, ABBA, etc. [15 Marks]

Answer:
import java.util.Scanner;
class PalindromeCheck {
    boolean Palin(String s) {
        String rev = "";
        for (int i = s.length() - 1; i >= 0; i--) {
            rev += s.charAt(i);
        }
        return s.equalsIgnoreCase(rev);
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter a string:");
        String str = sc.next();
        PalindromeCheck obj = new PalindromeCheck();
        if (obj.Palin(str))
            System.out.println("It is a Palindrome.");
        else
            System.out.println("It is not a Palindrome.");
    }
}

Teacher's Note:
a) Reversing a string by iterating backwards from the last index is a standard approach.
b) Using equalsIgnoreCase handles case consistency for words like Madam or MADAM.