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Values and Data Types

Solutions for Computer Applications, Class 10, ICSE

Assignment Questions

25 questions

Question 1

Why does Java use the Unicode character set?

Assignment Questions

Answer:

Unicode can represent nearly all languages of the world like English, Hindi, Bengali, Kannada, Arabic, Japanese, etc. Java uses unicode so that applications developed using Java can support a wide range of languages rather than just being limited to English.

Question 2

What are escape sequences in Java? Give three examples.

Assignment Questions

Answer:

An escape sequence is a set of characters that has a special meaning to the Java compiler. In the escape sequence, a character is preceded by a backslash (\). Some examples of escape sequences are \n, \' and \t.

Question 3

What is the result of evaluating the following expression?
(3 + 6 * 7) / 3 + 2

Assignment Questions

Answer:

    (3 + 6 * 7) / 3 + 2
⇒ (3 + 42) / 3 + 2
⇒ 45 / 3 + 2
⇒ 45 / 3 + 2
⇒ 15 + 2
⇒ 17

Question 4

What is a token in Java? Name the tokens available in Java.

Assignment Questions

Answer:

All characters in a Java program are grouped into symbols called Tokens. As you know, a computer program consists of a set of instructions called statements. A statement is composed of various components. Each individual component of a programming statement is referred to as a token. Keywords, Identifiers, Operators, Separators and Literals are five tokens in Java.

Question 5

Why can a keyword not be used as a variable name?

Assignment Questions

Answer:

Keywords are reserved words that have a special meaning to the Java compiler. As Java compiler reserves these words for its own use so they are not available as names for variables or methods.

Question 6

Which of the following are Java keywords?
area, input, class, public, int, x, y, radius, long, Hello java

Assignment Questions

Answer:

class, public, int, long are Java keywords.

Question 7

What are identifiers in Java? List three identifier formation rules.

Assignment Questions

Answer:

Identifiers are used to name different parts of a program such as variables, methods, classes, objects, etc. Three identifier formation rules are:

  1. An an identifier can be a sequence of alphabets, digits, underscore and dollar sign characters only.
  2. Identifiers cannot start with a digit.
  3. An identifier must not be a Keyword or a Boolean or null literal.

Question 8

Explain the following statement — "In Java, total, Total, ToTaL, and TOTAL are all different identifiers."

Assignment Questions

Answer:

Java is a case sensitive language. total, Total, ToTaL, and TOTAL have the same set of letters but they differ in the case of these letters. Therefore, Java considers each of them as a different identifier.

Question 9

Which of the following are invalid identifiers?

i. ten
ii. "Hello"
iii. 5678
iv. Coffee
v. $dollar
vi. 4Variables
vii. _var

Assignment Questions

Answer:

  • "Hello" is invalid as identifiers cannot contain double quotes.
  • 5678 is invalid as identifiers cannot start with a digit.
  • 4Variables is invalid as identifiers cannot start with a digit.

Question 10

How would you print characters like \, ' and " in Java?

Assignment Questions

Answer:

We can print characters like \, ' and " using escape sequences i.e. preceding it with a backslash (\) symbol.

Question 11

Distinguish between the following:

i. Token and Identifier

Assignment Questions

Answer:

TokenIdentifier
Each individual component of a programming statement is referred to as a token.Identifiers are fundamental building blocks of the program and are used to name different components of a program such as variables, methods and objects.
Tokens in Java are categorised into 5 types — Keywords, Identifiers, Literals, Punctuators, Operators.Identifier is a type of token in Java.

ii. Keyword and Identifier

KeywordIdentifier
Keywords have a special meaning for Java compiler.Identifiers are used to name different components of a program such as variables, methods and objects.
Keywords are reserved by the compiler for its own use.An identifier must not be a Keyword.

iii. Character and String Constant

Character ConstantString Constant
Character Constants are written by enclosing a character within a pair of single quotes.String Constants are written by enclosing a set of characters within a pair of double quotes.
Character Constants are assigned to variables of type char.String Constants are assigned to variables of type String.

iv. Integer and float Constant

Integer ConstantFloat Constant
Integer Constants represent whole number values like 2, -16, 18246, 24041973, etc.Float Constants represent fractional numbers like 3.14159, -14.08, 42.0, 675.238, etc.
Integer Constants are assigned to variables of data type — byte, short, int, long, charFloat Constants are assigned to variables of data type — float, double

Question 12

Distinguish between "A" and 'A'.

Assignment Questions

Answer:

"A" is a string literal of length 1 containing the letter A in uppercase whereas 'A' is a character literal having value of A in uppercase.

Question 13

What is wrong with the following statement?
    float flt = 7895.0345;

Assignment Questions

Answer:

This statement is trying to assign a double literal to a float variable so it will result in a syntax error of incompatible types (possible lossy conversion from double to float). To fix it we need to a f or F at the end of the double literal to make it a float literal as shown below:
    float flt = 7895.0345f;

Question 14

Describe primitive data types in Java.

Assignment Questions

Answer:

Primitive data types are fundamental data types that are an integral part of the Java language and are used to declare a variable.

Question 15

List the size of primitive data types in Java.

Assignment Questions

Answer:

Data TypeSize in Bytes
byte1
short2
int4
long8
float4
double8
char2
boolean1

Question 16

Which integer and floating point data types take up the same number of bits in computer memory?

Assignment Questions

Answer:

Both, int and float take up 32 bits in memory. Similarly, both long and double take up 64 bits in memory.

Question 17

What is variable initialisation in Java? What are the default values of the following type of variables? short, int, long, float, double, and char.

Assignment Questions

Answer:

Variable initialisation means assigning value to a variable for the first time. Below are the default values of the different data types:

Data TypeDefault Value
short0
int0
long0L
float0.0f
double0.0d
char'\u0000'

Question 18

Provide the declaration for two variables called xCoordinate and yCoordinate. Both variables are of type int and both are to be initialised to zero in the declaration.

Assignment Questions

Answer:

int xCoordinate = 0;  
int yCoordinate = 0;

OR

int xCoordinate = 0, yCoordinate = 0;

Question 19

Write a Java assignment statement that will set the value of the variable interestAmount to the value of the variable balanceAmount multiplied by the value of the variable rate. The variables are of type double.

Assignment Questions

Answer:

double interestAmount = balanceAmount * rate;

Question 20

Explain the statement, "a well-documented code is as important as the correctly working code".

Assignment Questions

Answer:

Writing fully commented code is a good programming style. The primary purpose of comments is to document the code so that even a layman can understand the purpose of the written code. Hence, a well-documented code is as important as the correctly working code.

Question 21

How can you write single line comments in Java?

Assignment Questions

Answer:

Single line comments in Java can be written using //. For example:

// This is an example of single line comment.

Question 22

Write a Java constant declaration that gives the name TAX_RATE to the value 15%.

Assignment Questions

Answer:

final int TAX_RATE = 15;

Question 23

If you want to change the precedence of operations in an expression, which symbols do you use?

Assignment Questions

Answer:

Brackets — () can be used to change operator precedence.

Question 24

What are symbolic constants? How are they useful in writing programs?

Assignment Questions

Answer:

Memory locations whose values cannot be changed within a program are called constants or symbolic constants. The advantages of symbolic constants are:

  1. It improves the readability of the program and makes it easier for someone to understand the code.
  2. Any unintentional changes to such variables are flagged by the compiler.
  3. Later, if there is a change in the value of such variables (e.g. interest rate changed), you just need to modify its value at one place and all the other occurrences will be taken care of automatically.

Question 25

What is the output produced by the following lines of program code?

char x, y;
x = 'y';
System.out.println(x);
y = 'z';
System.out.println(y);
x = y;
System.out.println(x);
Assignment Questions

Answer:

Below is the output produced by this code:

y
z
z

Variable x is assigned a value of character y so the first println prints y. Variable y is assigned a value of character z so the second println prints z. After that variable x is assigned the value of variable y which is the character z so last println prints z.

Multiple Choice Questions

20 questions

Question 1

Java uses ........... character set.

  1. ASCII Only
  2. Extended ASCII Only
  3. Unicode ✓
  4. None of these
Multiple Choice Questions

Answer:

Question 2

ASCII stands for ...........

  1. American Standard Code for Information Interchange ✓
  2. American Simulated Code for Information Interchange
  3. American Standard Code for Interchange of Information
  4. American Standard Code for Interaction of Information
Multiple Choice Questions

Answer:

Question 3

ASCII is ...........

  1. 6-bit set of codes
  2. 8-bit set of codes
  3. 7-bit set of codes ✓
  4. 16-bit set of codes
Multiple Choice Questions

Answer:

Question 4

Extended ASCII is ...........

  1. 6-bit set of codes
  2. 8-bit set of codes ✓
  3. 7-bit set of codes
  4. 16-bit set of codes
Multiple Choice Questions

Answer:

Question 5

The smallest individual component in a program is called ...........

  1. Token ✓
  2. Identifier
  3. Keyword
  4. Method
Multiple Choice Questions

Answer:

Question 6

Which of the following is not a token?

  1. Keyword
  2. Identifier
  3. Operator
  4. Procedure ✓
Multiple Choice Questions

Answer:

Question 7

Which of the following is a keyword?

  1. character
  2. break ✓
  3. object
  4. attribute
Multiple Choice Questions

Answer:

Question 8

Which of the following is not a legal identifier?

  1. _room
  2. $PayAmount
  3. 10thClass ✓
  4. nullValue
Multiple Choice Questions

Answer:

Question 9

Which of the following is a default value of float data type?

  1. 0
  2. 0float
  3. 0f
  4. 0.0f ✓
Multiple Choice Questions

Answer:

Question 10

Which of the following is a default value of boolean data type?

  1. true
  2. false ✓
  3. null
  4. void
Multiple Choice Questions

Answer:

Question 11

Which of the following is an invalid integer?

  1. 2222
  2. 22222
  3. 222 22 ✓
  4. 222
Multiple Choice Questions

Answer:

Question 12

Which of the following is not a character literal?

  1. '\n'
  2. "n" ✓
  3. 'n'
  4. All of these
Multiple Choice Questions

Answer:

Question 13

Which of the following punctuator is the statement terminator in Java?

  1. ; ✓
  2. .
  3. ,
  4. All of these
Multiple Choice Questions

Answer:

Question 14

Which of the following is not a primitive data type in Java?

  1. boolean
  2. short
  3. float
  4. class ✓
Multiple Choice Questions

Answer:

Question 15

What is the size of a long data type in Java?

  1. 32 bits
  2. 64 bits ✓
  3. 48 bits
  4. Long data type is not supported in Java.
Multiple Choice Questions

Answer:

Question 16

What is the size of a boolean data type in Java?

  1. 1 bit
  2. 16 bits
  3. 8 bits ✓
  4. Boolean data type does not take any space in memory.
Multiple Choice Questions

Answer:

Question 17

Single line comments can be added using ...........

  1. //
  2. /* */
  3. \
  4. Both A and B ✓
Multiple Choice Questions

Answer:

Question 18

Which of the following changes a variable declaration into a constant?

  1. const
  2. constant
  3. static
  4. final ✓
Multiple Choice Questions

Answer:

Question 19

The ASCII codes of A-Z are represented by decimal range ...........

  1. 65-90 ✓
  2. 66-91
  3. 97-122
  4. 98-123
Multiple Choice Questions

Answer:

Question 20

Which of the following is a primitive data type?

  1. array
  2. interface
  3. class
  4. boolean ✓
Multiple Choice Questions

Answer:

State whether the given statements are True or False

15 questions

Question 1

Java supports the use of the ASCII character set only.
False

State whether the given statements are True or False

Answer:

Question 2

The ASCII code for character 'Z' is 90.
True

State whether the given statements are True or False

Answer:

Question 3

The smallest unit in a Java program is known as token.
True

State whether the given statements are True or False

Answer:

Question 4

The Unicode character set uses 8 to 32 bits per character.
True

State whether the given statements are True or False

Answer:

Question 5

In an escape sequence, a character is preceded by a backward slash (\).
True

State whether the given statements are True or False

Answer:

Question 6

In Java, an identifier can begin with a $ sign.
True

State whether the given statements are True or False

Answer:

Question 7

The boolean data type is used for storing logical values.
True

State whether the given statements are True or False

Answer:

Question 8

Java offers five types of tokens.
True

State whether the given statements are True or False

Answer:

Question 9

Identifiers in Java may be of any length.
True

State whether the given statements are True or False

Answer:

Question 10

The char data type reserves 8 bits in memory.
False

State whether the given statements are True or False

Answer:

Question 11

Default value of reference data type is null.
True

State whether the given statements are True or False

Answer:

Question 12

To designate a literal constant of the type float, you must append the letter L to it.
False

State whether the given statements are True or False

Answer:

Question 13

Default value of char data type is '\u0000'.
True

State whether the given statements are True or False

Answer:

Question 14

If a literal constant contains a decimal point, then it is of the type double by default.
True

State whether the given statements are True or False

Answer:

Question 15

A variable can be used in a Java program even if it has not been declared.
False

State whether the given statements are True or False

Answer: