data representation

Question 1

What is a bit?

Answer 1

A bit is the smallest unit of data in computing and can have a value of 0 or 1.

Question 2

What is a byte?

Answer 2

A byte is a group of 8 bits.

Question 3

What is the base of the binary number system?

Answer 3

Binary is base 2.

Question 4

What is the base of the hexadecimal number system?

Answer 4

Hexadecimal is base 16.

Question 5

What are the hex digits for values 10 to 15?

Answer 5

A = 10, B = 11, C = 12, D = 13, E = 14, F = 15.

Question 6

What is the purpose of hexadecimal in computing?

Answer 6

It simplifies long binary numbers and is easier for humans to read.

Question 7

What is ASCII?

Answer 7

A character encoding system where each letter or symbol is represented by a binary value.

Question 8

What is an image represented by in computers?

Answer 8

Pixels, where each pixel has a binary value representing colour.

Question 9

What is the term for the number of bits used to store each pixel?

Answer 9

Colour depth.

Question 10

What is a sound sample?

Answer 10

A measurement of the sound wave’s amplitude at a specific point in time.

Question 11

What are the main units of data from smallest to largest?

Answer 11

Bit, Byte, Kilobyte (KB), Megabyte (MB), Gigabyte (GB), Terabyte (TB).

Question 12

What is the purpose of data compression

Answer 12

To reduce the size of files, saving storage space and allowing faster transmission.

Question 13

What is lossless compression?

Answer 13

A method that reduces file size without losing any data. The original file can be fully restored.

Question 14

What is lossy compression?

Answer 14

A method that removes some data permanently, reducing file size but also quality.

Question 15

What number base does binary use?

Answer 15

Base 2.

Question 16

How is text represented in computers?

Answer 16

: Using character sets such as ASCII or Unicode.

Question 17

How is sound represented in a computer?

Answer 17

Sound is captured as an analogue signal and converted to digital using sampling.

Question 18

What is sampling?

Answer 18

Measuring the amplitude of an analogue sound wave at regular intervals.

Question 19

What two factors affect the quality of a sampled sound?

Answer 19

Sample rate (samples per second) and bit depth (bits per sample).

Question 20

What happens when the sample rate increases?

Answer 20

The sound quality improves and file size increases.

Question 21

What is the formula to calculate sound file size?

Answer 21

File size = Sample rate × Bit depth × Duration × Number of channels.

Question 22

How are images stored in a computer?

Answer 22

As a grid of pixels, with each pixel assigned a binary value to represent its colour.

Question 23

What is resolution in an image?

Answer 23

The number of pixels in an image; higher resolution means more detail and larger file size.

Question 24

What is colour depth?

Answer 24

The number of bits used to represent each pixel’s colour

Question 25

What happens when colour depth increases?

Answer 25

The image can show more colours, but the file size increases.

Question 26

: What is metadata in an image file?

Answer 26

Extra data stored with the image such as height, width, colour depth, and date taken.

Question 27

What is ASCII?

Answer 27

ASCII (American Standard Code for Information Interchange) is a character set that uses 7 bits to represent 128 characters.

Question 28

What types of characters does ASCII include?

Answer 28

Upper and lowercase letters, digits, punctuation, and control codes.

Question 29

What is extended ASCII?

Answer 29

A version of ASCII that uses 8 bits to represent 256 characters, allowing for extra symbols.

Question 30

What is a character set?

Answer 30

A character set is a collection of characters that a computer can recognize and store using binary codes.

Question 31

Why is Unicode used instead of ASCII sometimes?

Answer 31

Unicode supports thousands of characters from many languages, unlike ASCII which is limited to English.

Question 32

What is compression?

Answer 32

Compression is the process of reducing the file size of data to save storage space or reduce transmission time.

Question 33

What is lossless compression?

Answer 33

Lossless compression reduces file size without losing any data. The original file can be perfectly restored.

Question 34

What is lossy compression?

Answer 34

Lossy compression reduces file size by removing some data permanently. The original file cannot be fully restored.

Question 35

Give an example of a file type that uses lossless compression.

Answer 35

PNG image files use lossless compression.

Question 36

Give an example of a file type that uses lossy compression.

Answer 36

MP3 audio files use lossy compression.

Question 37

What are the advantages of lossless compression?

Answer 37

No quality is lost, and the original data can be fully restored.

Question 38

What are the advantages of lossy compression?

Answer 38

It significantly reduces file size, making it ideal for streaming and saving space.

Question 39

What is a common use of lossless compression?

Answer 39

Text documents, ZIP files, and software backups.

Question 40

What is a common use of lossy compression?

Answer 40

Multimedia files such as music, videos, and photographs for web use.

Question 41

Why wouldn’t lossy compression be used for a text file?

Answer 41

Because even a small data loss can corrupt the meaning, making it unreadable or incorrect.