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WorksheetsiGCSE Computer Science: Data
Total questions: 69
Worksheet time: 42mins
What is the binary number 10101 in decimal?
1000
8
21
15
Computers use binary to represent data and programs because ...
CPUs have millions of transistors which have two possible states
Boolean logic only has two possible states
Alan Turing suggested that in an academic paper
it's a simpler system than decimal
Which is the binary version of 13?
1111
1110
1101
1001
With 6 bits of data how many different items of data can be represented?
64
32
128
6
How many bits are there in one byte of data?
8
2
10
1000
How many bits of data do you need to represent 512 different values?
9
512
8
10
Which is the character set of the hexadecimal number system?
0, 1
0, 1, 2, 3, 4, 5, 6, 7, 8, 9
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
Why is the hexadecimal number system useful in Computer Science?
Because 16 is a power of 2
Because it shortens binary data by 75%
Because computers originally only understood hexadecimal
Because it's easier to do calculations in hexadecimal than binary
Select all answers that correctly define one byte of data
8 bits
1/1024 of a Kibibyte
0 or 1
2 nybbles
Amount of storage space required by one character in the Extended ASCII system
What is 00001101 + 10101010
10110111
11110101
10111000
01001000
In what ways is Sign and Magnitude representation different from Two's complement?
More than one way to represent zero
Binary addition does not always give correct result
Takes up more storage space
Can represent a smaller range of values
In any binary number, what is the Most Significant Bit (MSB)?
Bit with the highest place value
Most important bit
Bit furthest to the right
Bit furthest to the left
What is the 8-bit Two's complement representation of -28?
11100100
11100101
00011010
11001100
What is the hexadecimal number for the binary number 10111001
B9
A9
B10
9B
Where are hexadecimal numbers used (select all that apply)
IPv4 addresses
IPv6 addresses
MAC addresses
24 bit RGB colours
Memory dumps
What is the largest number that can be represented by two digits in hexadecimal?
AA
FF
255
4
Which is the odd one out?
a nybble
1110
half a byte
4 bits
4
ASCII is an encoding system for text. What does ASCII stand for?
American Standard Code for Information Interchange
All System Code In Internet
American Simple Code for Interesting Information
Alpha Super Code Input Information
How many bits was used to encode the original ASCII character set?
7
8
16
4
What type of data is stored in the first 32 ASCII codes?
Control codes
Letters A-Z
Numbers
Punctuation symbols
The Extended ASCII system uses 8 bits per character instead of 7 bits. How many different characters can be represented in 8 bits?
1024
8
128
256
If 01000001 (65) is the ASCII code for the letter 'A' what is the binary code for 'E'?
01000011
01000101
01000110
01000111
If 065 is the ASCII code for 'A' and 097 is 'a', what text is encoded by: 085 110 105 099 111 100 101 032 097 110 100 032 065 083 067 073 073
Compute the codes
Unicode and ASCII
ASCII is for text
Computing is cool
If 097 is the ASCII code for lower case 'a', which is the correct encoding of the text "The quick brown fox"
084 104 101 032 113 117 105 099 107 032 098 114 111 119 110 032 102 111 120
067 117 114 105 111 117 115 032 103 114 101 101 110 032 105 100 101 097 115
067 111 109 112 117 116 105 110 103 032 105 115 032 099 111 111 108 033 033
084 104 101 032 115 108 111 119 032 111 108 100 032 104 111 114 115 101 032
How many characters are currently represented (in 2017) by the Unicode system?
21,977
1,250,569
75,004
136,690
UTF-8 is the most common encoding system on the web for Unicode. What does UTF stand for?
Universal Text Format
Unicode Transformation Format
Unicode Text Free
Use The Force
What version is the latest and most current version of Unicode?
9.0
10.0
12.0
5.0
Pixels get their colour from a combination of which colours?
cyan magenta yellow black
red green blue
primary colours
black white
Which factors affect the file size of a bitmap image? (select all that apply)
pixel density
image dimensions
colour depth
software used to create it
format of image meta-data
If an image has a colour depth of 8 bits then the number of possible colour shades is ... ?
256
8
16
2014
If an image has a colour depth of 65,536 colours, then the number of bits used to represent each pixel is ...
64
10
8
16
The True Color bitmap standard uses 24 bits to represent every pixel. How many possible colour shades does this allow?
16,777,216
65,536
24
48
Which of these image file formats involves lossy compression?
.gif
.png
.jpg
.bmp
Which of these image file formats involves lossless compression? (select all that apply)
.gif
.png
.jpg
.bmp
Which image file format is uncompressed?
.bmp
.png
.jpg
.gif
The density of pixels in an image is measured by ...?
pixels per inch
dots per cm
pixels per cm
width * height
What is the correct term for the amount of pixels that make up a digital image?
pixellation
resolution
resolvation
density
Pixels are normally stored using three RGB colour values that can range from 0 up to ...
7
256
255
16,700,000
What are the smallest elements of a digital image called?
colors
bits
dots
pixels
What piece of hardware is used to sample a sound wave?
Digital-analogue converter
Wave synthesizer
Microphone
Analogue-digital converter
What does the bit rate of a sampled sound refer to?
The number of bits used for 1 second of audio
The number of bits used for every sample
The final file size of the sampled sound
The speed at which the sampled sound is played back
What is the standard sampling frequency for CD audio?
20,000 Hz
44,100 Hz
33,300 Hz
96,000 Hz
What is the main uncompressed audio file format?
.mp3
.mp4
.wav
.mov
What is most commonly used compressed audio file format?
.wav
.mp3
.mp4
.ogg
One factor that affects the quality of digital audio is the bit depth. What does this refer to?
The number of bits used to store each sample
The overall size of the sampled sound
The number of bits needed for 1 second of audio
The number of samples taken every second
Which of these are factors in determining the amount of storage needed for a digitally sampled sound? (select all that apply)
The number of samples taken per second
The bit depth per sample
The length of the sampled sound
The range of wave frequencies present in the sound
The type of audio sampled (voice, music, etc)
Which of these are factors in determining the quality of a sampled sound? (select all that apply)
The number of samples taken per second
The number of bits used to store each sample
The length of the sampled sound in seconds
The range of wave frequencies present in the sound
Which of these variables affect the file size of a sampled sound? (select all that apply)
the bit depth
the sampling frequency
the bit rate
the length of the sampled sound
the type of sound (speech, music etc)
What is the name of a popular freeware audio manipulation software?
Soundshop
Sonacity
Audacity
Wave Studio
Which of these are recognised types of file compression? (select all that apply)
lossless
lossy
superchannel
standard
redundant
What are the main reasons to compress data? (select all that apply)
To reduce secondary storage space
To maximise the available RAM memory
To speed up network transmission times
To optimise the data
To reduce packet congestion on networks
Which of these are recognised lossless compression algorithms? (select all that apply)
RLE
LZ-77 (dictionary coder)
Caesar cipher
Merges sort
What is the correct Run-length encoding for the data: cccmmmmmsssssdcccccc
3c5m5s1d6c
c3m5s5d1c6
cmsdc35516
cccmmmmmsssssdcccccc
Which of these image file formats support lossless compression techniques? (select all that apply)
JPG
PNG
GIF
BMP
SVG
Which of these audio file formats support lossy compression?
FLAC
MP3
WAV
OggPCM
WMA
What is the correct order of memory storage units from smallest to largest?
KiB MB MiB GB TiB
KiB MiB MB TiB GB
MB MiB KB GB TiB
KB GB MB MiB TiB
What is the name of the lossy compression algorithm used in JPG image compression?
Discrete Cosine Transform
Abstract Sinusoidal Mutation
Run-length encoding
LZ-77
On which of these data strings would you expect a dictionary-based lossless compression algorithm like LZ-77 to achieve the highest compression ratio?
This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop.
lpumf yxidt mgcwo aiyfj nqyuj znhja vjacx vewcf jmxgy suqwj dvnzq zcops gpsbz rgxox sxypw mvvun cxxda dfixa burli sitbh ljprx uqehk aggap btnep ispxx zmuus ndbyd hwplq zbwgd pznkr zkdbp ssedo
Grumpy wizards make toxic brew for the evil Queen and Jack
Old MacDonald had a farm
E-I-E-I-O
And on his farm he had a cow
E-I-E-I-O
With a moo-moo here
And a moo-moo there
Here a moo, there a moo
Everywhere a moo-moo
Old MacDonald had a farm
E-I-E-I-O
On which piece of data would you expect the run-length encoding algorithm to achieve the highest compression ratio?
Nellie the Elephant packed her trunk
And said goodbye to the circus
Off she went with a trumpety-trump
Trump, trump, trump
Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great
What type of modelling is being exploited in mp3 audio lossy compression?
psychological
psychokinetic
physiological
psychoacoustic
Asymmetric encryption is when ...
a message is encrypted and decrypted using two different keys: a public one and a private one
only one message can be encrypted at a time
An encrypted message is received, but there is no requirement to return an encrypted message
There is no key available to decrypt an encrypted message that has been received
Which of these encryption algorithms do you need to know about for iGCSE Computer Science? (select all that apply)
Caesar
Pigpen
Vigenère
Rail-fence
Vernam
Which is a Caesar cipher?
Which is a Vigenère cipher?
Which is a Pigpen cipher?
Which is a rail-fence cipher?
Select all the statements that are true about the Caesar cipher
It was first used by Roman Emperor Julius Caesar
It is a very secure form of encryption
It does not provide much information 'leakage' for a cryptographer
It can be easily cracked using frequency analysis techniques
It is an example of a substitution cipher
