CBSE/Karnataka PU Board PUC I CHAPTER 2 : Encoding Schemes and Number System 1 Mark Questions (20)

1 Mark Questions (20)

What is the binary language composed of?
A. 0 and 1
B. 1 and 2
C. 0 and 2
D. A and B
Answer: A. 0 and 1
What does ASCII stand for?
A. American Standard Code for Integrated Information
B. Asian Standard Code for Information Interchange
C. American Standard Code for Information Interchange
D. Applied System for Coding Information
Answer: C. American Standard Code for Information Interchange
What is the base value of the binary number system?
A. 8
B. 2
C. 10
D. 16
Answer: B. 2
Which number system uses digits 0-7?
A. Decimal
B. Hexadecimal
C. Octal
D. Binary
Answer: C. Octal
ASCII was developed to standardise which aspect?
A. Programming
B. Character Representation
C. Device Management
D. Security
Answer: B. Character Representation
Which encoding scheme is used for Indian language scripts?
A. ASCII
B. ISCII
C. Unicode
D. Base64
Answer: B. ISCII
Which number system is most commonly used by humans?
A. Binary
B. Octal
C. Hexadecimal
D. Decimal
Answer: D. Decimal
What is the hexadecimal notation for the decimal value 10?
A. 10
B. A
C. 1A
D. 1010
Answer: B. A
What is the minimum number of bits used by ASCII?
A. 8
B. 10
C. 7
D. 16
Answer: C. 7
Which code is represented as 65 in ASCII?
A. B
B. a
C. A
D. Space
Answer: C. A
Which scheme is a superset of ASCII?
A. ISCII
B. Unicode
C. EBCDIC
D. UTF8
Answer: B. Unicode
What symbols are used in hexadecimal numbers?
A. 0-9, A-F
B. 0-7, A-H
C. 0-9, A-Z
D. 0-5, F-K
Answer: A. 0-9, A-F
The process of converting text/data into encoded form is called:
A. Decoding
B. Encryption
C. Coding
D. Encoding
Answer: D. Encoding
What does ISCII use as its code range for additional Indian languages?
A. 150–250
B. 200–256
C. 128–255
D. 100–128
Answer: C. 128–255
Which value in hexadecimal is equal to decimal number 15?
A. E
B. F
C. 15
D. 0X15
Answer: B. F
Which one is NOT a number system used in computers?
A. Decimal
B. Binary
C. Quinary
D. Octal
Answer: C. Quinary
Octal base value is:
A. 7
B. 8
C. 16
D. 10
Answer: B. 8
Which encoding supports all world-written languages?
A. ASCII
B. ISCII
C. Unicode
D. EBCDIC
Answer: C. Unicode
The hexadecimal value for binary 1111 is:
A. F
B. E
C. 15
D. A
Answer: A. F
Which number system uses positional notation and bases?
A. Decimal
B. Binary
C. Octal
D. All of the above
Answer: D. All of the above

2 Mark Questions (20)

What is the main reason for using encoding schemes in computers?
Answer: To standardise text representation so that computers and devices interpret, store, and exchange data accurately, regardless of manufacturer or language.
Describe the difference between ASCII and Unicode.
Answer: ASCII uses 7 bits for English characters, representing up to 128 values; Unicode encodes thousands of symbols from all world languages and is a superset of ASCII.
What is the base and symbol set for hexadecimal system?
Answer: Hexadecimal has base 16, using symbols 0-9 and A-F where A=10 and F=15.
How is letter 'A' encoded in ASCII, and its binary representation?
Answer: 'A' is coded as decimal 65; binary representation is 1000001.
What is positional value in number systems?
Answer: It refers to the power of the base relative to the position of each digit; each position (left to right) affects value as base^position.
Distinguish between ISCII and ASCII.
Answer: ASCII encodes only English with 128 values; ISCII is 8-bit, retains ASCII's 128 codes, uses extra codes for Indian scripts.
State a practical use of hexadecimal numbers in computing.
Answer: Memory addresses and web colour codes use hexadecimal for compactness (e.g., FF0000 for red).
Why are octal and hexadecimal systems preferred for binary grouping?
Answer: Binary numbers are grouped into sets of 3 (octal) or 4 (hexadecimal) for compact and readable representation.
What is UTF-8?
Answer: UTF-8 is a Unicode encoding that uses 8 bits for characters, is space-efficient, and compatible with ASCII.
Give decimal value and binary for hexadecimal 'A3'.
Answer: A3: Decimal = 163; Binary = 10100011
What is the key advantage of Unicode?
Answer: It provides a unique, standardised code for every character of every language, improving compatibility and global communication.
What are the digits used in octal and their bit-group equivalents?
Answer: 0–7 in octal; each digit equals three binary bits.
How does binary relate to Boolean logic in computers?
Answer: Binary’s 0 and 1 values represent false and true in digital circuits, forming the basis of logic gates and computer operations.
What is the base of decimal, and why is it human-friendly?
Answer: 10; it matches our ten digits (0–9), used in everyday life.
Where are ASCII codes most commonly used today?
Answer: In computers, text files, internet protocols, and programming languages for standard English text encoding.
State the difference between encoding and encryption.
Answer: Encoding converts information to a usable standard; encryption secures it into a cipher to prevent unauthorised access.
What are colour codes in web design?
Answer: Hexadecimal values representing RGB colours on webpages, e.g., #FFFFFF is white.
What is the process of conversion from decimal to binary?
Answer: Divide decimal by 2, record remainders, and collect them in reverse to obtain binary.
Why is base indicated with subscript in numbers (e.g. 7010)?
Answer: To differentiate the number system (base 10 for decimal, base 2 for binary, etc.)
Which encoding is used in Hindi keyboard typing for computers?
Answer: ISCII and Unicode.

3 Mark Questions (20)

Explain how character encoding allows computer communication.
Answer: Character encoding maps each symbol to a specific code. When two systems use the same encoding (e.g., ASCII, Unicode), text exchanged between them is predictable and recognisable and isn't garbled.
Describe the conversion process from binary to decimal.
Answer: Each bit represents a base-2 position (2^n); multiply each bit by its positional value and sum to get decimal value.
Why was Unicode necessary after ASCII and ISCII?
Answer: ASCII and ISCII couldn't support all world languages and scripts; Unicode provides a universal, standard code point for every symbol, enabling multi-language computer usage.
How do hexadecimal numbers simplify memory addressing?
Answer: Long binary memory addresses are condensed into 4-bit hexadecimal digits, making them easier for programmers to read and remember.
Explain conversion of a decimal number with fractional part to binary.
Answer: Multiply fractional part successively by 2, write the integer parts in sequence for binary fraction.
What role does positional notation play in number bases?
Answer: Positional notation lets each digit's value depend on its position and base, allowing diverse number system representation (e.g., decimals, binaries).
What is the process for encoding a word like "DATA" using ASCII?
Answer: Replace each letter with its ASCII code, then its binary equivalent. D=68(1000100), A=65(1000001), T=84(1010100), A=65(1000001).
What is the difference between UTF-16 and UTF-32 Unicode encodings?
Answer: UTF-16 uses 16 bits, packs more efficiently for most languages; UTF-32 uses 32 bits per character, making every character equally-sized but using more space.
Why do computers use binary internally despite humans’ use of decimal?
Answer: Binary matches the two states of digital hardware (on/off, true/false), enabling reliable processing and circuit design.
Explain why 3 bits are grouped in binary to obtain octal digits.
Answer: 2^3 = 8, so every group of 3 binary digits converts directly to one octal digit.
How are fractional binary numbers converted to octal or hexadecimal?
Answer: Group fractional bits into clusters of 3 (octal) or 4 (hexadecimal), pad with zeros as needed, then substitute corresponding octal/hex digits.
State two issues solved by standard encoding schemes.
Answer: Cross-platform text compatibility and language script representation.
What is the significance of positional value in non-decimal systems?
Answer: It determines digit value in systems (binary, octal, hex) for correct conversions.
How is the number 2578 converted to decimal?
Answer: (2×8^2) + (5×8^1) + (7×8^0) = 128+40+7=175
What encoding is best for multilingual digital documents?
Answer: Unicode, as it encodes characters for virtually all world languages.
Give one real-world example where hexadecimal is used outside memory addressing.
Answer: In web design for colour specification.
Describe octal to binary conversion process.
Answer: Replace each octal digit with its 3-bit binary equivalent.
Why is ASCII insufficient for modern computing?
Answer: It covers only English letters and symbols; lacks support for other languages/scripts.
What is the difference between encryption and encoding?
Answer: Encoding standardises data; encryption secures data by making it unreadable without a key.
What does a hexadecimal colour code represent in HTML?
Answer: The code represents RGB values for colours (e.g., #FF0000 for red).

5 Mark Questions (20)

Here are detailed answers for the 5 mark questions based on your "Encoding Schemes and Number System" PDF (KECS102).

Q61: Describe in detail the differences and applications of ASCII, ISCII, and Unicode encoding schemes.
Answer:

ASCII (American Standard Code for Information Interchange) was developed in the 1960s to provide a standard way of representing English keyboard characters in computers using a 7-bit code (allows for 128 unique characters, including upper and lowercase letters, digits, punctuation, and control codes). ASCII makes sure that characters are interpreted the same way on any device using the scheme, providing compatibility and predictability. However, its limitation is that it only encodes English characters.
ISCII (Indian Script Code for Information Interchange) was designed in India in the 1980s for digitising Indian language scripts. ISCII uses an 8-bit code, retaining all 128 ASCII codes and utilizing the extra range (128–255) for Indic language aksharas (characters) and symbols. ISCII enabled computers to encode and display Indian languages and is crucial for databases, applications, and web content needing regional language support.
Unicode is an international standard designed to encode every character from every written language in the world, overcoming limitations of ASCII, ISCII, and other encodings. Unicode provides unique numbers for every character, regardless of platform, program, or language, and supports encoding via UTF-8, UTF-16, and UTF-32. Unicode covers thousands of languages, ensuring cross-platform text compatibility and simple internationalisation. Unicode is now the standard for web and modern operating systems, supporting global communication and content creation.
Applications:
- ASCII: Text files, programming languages, network protocols.
- ISCII: Indian language wordprocessors, databases, regional websites.
- Unicode: Multilingual documents, web pages, cross-device texts, mobile apps.

Q62: Explain the conversion of a decimal number to binary, octal, and hexadecimal with examples.
Answer:
To convert a decimal number to another base:

Binary:
Divide the decimal number by 2 repeatedly, noting remainders each time, until quotient is 0. Write remainders in reverse order.
Example: Convert 65 to binary.


text
65 ÷ 2 = 32 remainder 1  
32 ÷ 2 = 16 remainder 0  
16 ÷ 2 = 8  remainder 0  
8 ÷ 2  = 4  remainder 0  
4 ÷ 2  = 2  remainder 0  
2 ÷ 2  = 1  remainder 0  
1 ÷ 2  = 0  remainder 1  
Reverse remainders: 1000001

So, 65₁₀ = 1000001₂

Octal:
Divide by 8 repeatedly; reverse remainders.


text
65 ÷ 8 = 8 remainder 1  
8 ÷ 8 = 1 remainder 0  
1 ÷ 8 = 0 remainder 1  
Reverse: 101

65₁₀ = 101₈

Hexadecimal:
Divide by 16 repeatedly, noting remainders.


text
65 ÷ 16 = 4 remainder 1  
4 ÷ 16 = 0 remainder 4  
Reverse: 41  
**
65₁₀ = 41₁₆**

Repeat similarly for other decimal numbers.

Q63: Elaborate the role and representation of hexadecimal numbers in computers.
Answer:
Hexadecimal is a base-16 number system using digits 0–9 and A–F (A=10 ... F=15). Each hex digit represents 4 binary digits, making it compact for digital systems.

Role:
- Memory addresses: Instead of long binary addresses, memory is addressed in hex for readability (e.g., binary 1111000011110001 = F0F1 in hex).
- Colour codes in web design: RGB values use hexadecimal (#FF0000 for red).
- Debugging and programming: Hex is used to examine binary content and low-level hardware registers.
Representation:
- Each group of 4 bits in binary is equal to one hex digit.
- Hex values are often prefixed with "0x" or subscript 16 (e.g., 7A16).
Applications:
- Hex simplifies human interaction with large binary values, and is an efficient way to represent, enter and read important system parameters.

Q64: With examples, explain how ASCII encoding is applied for English text conversion and display.
Answer:
ASCII assigns a unique numeric code for each character (e.g., 'A' = 65, 'B' = 66, 'a' = 97, space = 32).
To convert a word "DATA":

D = ASCII 68 = 1000100 (binary)
A = ASCII 65 = 1000001
T = ASCII 84 = 1010100
A = ASCII 65 = 1000001
On a computer, each letter of "DATA" is stored and transmitted by referencing its ASCII code and converted to binary for hardware understanding.
When text is displayed or exchanged between devices, the numeric ASCII codes are interpreted by all systems as the same character, ensuring compatibility.

Q65: Outline the process and importance of conversion between number systems when programming or configuring systems.
Answer:

Process:
- To convert from decimal to binary: divide by 2 repeatedly, collect remainders.
- Binary to octal/hexadecimal: group bits in 3s (octal) or 4s (hexadecimal), map group to digit.
- Reverse for base-n to decimal: multiply each digit by base^position and sum.
Importance:
- Different systems and hardware use different bases. User interfaces and software expect decimal; hardware, binary.
- Memory addresses, machine instructions, colours are compactly represented in hexadecimal.
- Programmers/interfacing systems need precise conversions during coding, debugging, protocol decoding.
- Ensures accuracy, prevents data misinterpretation, and supports efficient hardware/software development.

Q66: Explain how Unicode encoding enhances computing in multilingual and web environments.
Answer:
Unicode provides unique codes for all languages, so text in different scripts can be represented, processed, and displayed without encoding conflicts.

UTF-8, UTF-16, UTF-32 offer efficient storage and compatibility.
Web pages (e.g., HTML, XML) use Unicode for global accessibility.
Mobile apps, databases, and operating systems use Unicode to support cross-language input/output.
No need for special fonts/tools—most devices and OSs support Unicode.
Facilitates international usage, collaboration, and multicultural content.

Q67: Discuss the impact of encoding schemes on secure communication and data privacy.
Answer:
Encoding schemes standardise data representation so two systems can interpret text/data identically.

Security: Encoding is the basis for encryption, which transforms readable data into cipher text for safe transmission.
Encoded data can be made unreadable by using agreed schemes, preventing misinterpretation.
Privacy: Proper encoding ensures only authorised users decode the intended content, critical for passwords, private messages, and authentication.
In combination with encryption, encoding is fundamental for modern secure communication (emails, online forms, digital signatures).

Q68: Detail the conversion process of a binary fractional number to decimal, octal, and hexadecimal.
Answer:

Binary Fraction to Decimal: Each digit after the point is multiplied by 2^-n (n starts at 1). Sum for decimal.
Example: 0.101 = 1×2^-1 + 0×2^-2 + 1×2^-3 = 0.5 + 0 + 0.125 = 0.625
Binary Fraction to Octal: Group bits in sets of 3 from the point to the right and convert each group.
Example: 0.101101 → group as 101,101 = 5,5 → 0.55 octal
Binary Fraction to Hexadecimal: Group bits in sets of 4 and convert.
Example: 0.1011 → 1011 = B → 0.B hex

Q69: How does the concept of positional notation empower different number systems?
Answer:
Positional notation gives a digit its value based on its position and the base (radix) of the system.

In decimal, digit "5" in '25' has value 5×10^0, "2" is 2×10^1.
Similarly, in binary: In 10101, rightmost "1" is 1×2^0, next is 0×2^1, etc.
This concept enables easy conversion between number systems, computation, and allows representing very large or small values compactly.

Q70: Step-by-step, how is the colour red encoded in web design using binary and hexadecimal?
Answer:
Red in RGB is represented as (255,0,0).

Binary: 255 = 11111111, 0 = 00000000
So, in 24-bit binary: 11111111 00000000 00000000
Hexadecimal: 255 = FF, so code is FF0000.
In web design, this is written as #FF0000.

Q71: Describe the significance and advantages of Unicode UTF-8 over other encodings.
Answer:
UTF-8 is compatible with ASCII and variable-length, using 1–4 bytes per character.

Good for English and multilingual text; smaller file sizes.
No byte order issues; easier to process and transmit.
Widely supported in browsers, applications, and protocols.

Q72: Convert the hexadecimal number 3A516 to decimal, showing calculation.
Answer:
3A5₁₆ = (3 × 16^2) + (10 × 16^1) + (5 × 16^0)
= (3 × 256) + (10 × 16) + (5 × 1)
= 768 + 160 + 5 = 933
So, 3A5₁₆ = 933₁₀

Q73: Discuss the representation and usage of number systems with fractions in digital technology.
Answer:
Fractional values are essential for representing non-integer data such as colours, audio signals, and sensor data.

Binary fractions capture analog signals after ADC conversion.
Octal/hexadecimal fractions simplify data grouping and storage.
Used in computer graphics, digital audio, and real-time measurements.

Q74: Why are grouping bits important for converting between binary and octal/hexadecimal?
Answer:
Groups of 3 bits represent one octal digit; 4 bits represent one hexadecimal digit.

This speeds up conversion, improves readability, and reduces errors.
Essential for hardware addressing, protocol design, and practical programming tasks.

Q75: Explain with example the conversion of a binary number (e.g., 10101100) to octal and hexadecimal.
Answer:

Octal: Group 3 bits — 010 101 100 → 2 5 4 → 254₈
Hexadecimal: Group 4 bits — 1010 1100 → A C → AC₁₆

Q76: Elaborate the cross-platform advantage of standard encoding schemes in global communication.
Answer:
Standard encoding like Unicode ensures that text and data are exchanged and interpreted correctly on all devices, operating systems, and platforms. Enables seamless e-mail, web, and software communication worldwide.

Q77: Discuss the importance of base value notation in digital systems.
Answer:
Base value notation specifies the number system and prevents errors in translation, computation, and programming, critical for digital system accuracy.

Q78: Demonstrate the process of converting fractional decimal 0.25 into binary.
Answer:
0.25 × 2 = 0.5 → write 0
0.5 × 2 = 1.0 → write 1
So, 0.25 = 0.01₂

Q79: How do number systems and encoding schemes contribute to computer programming?
Answer:
Programming involves working and converting different number systems (address calculation, loops, flags), with encoding schemes ensuring accurate data processing, storage, and exchange.

Q80: Explain why Unicode is preferred for typing and storing Indian languages in digital documents.
Answer:
Unicode supports all Indian scripts, provides unique code points for every symbol, avoids font/tool installations, enables compatibility across devices and platforms, and supports multilingual content creation and sharing.

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