Page 1 of 64
AQA A-LEVEL COMPUTER SCIENCE PAPER 2 EXAM
QUESTIONS WITH VERIFIED QUESTIONS DETAILED
RATIONALES GRADED A+
AQA A-LEVEL COMPUTER SCIENCE PAPER 2
Original Questions with Answers and Rationales
SECTION 1: FUNDAMENTALS OF DATA REPRESENTATION
Questions 1–30
1. How many bits are in a byte?
• A) 4
• B) 8
• C) 16
• D) 32
Answer: B) 8
Rationale: A byte consists of 8 bits.
2. What is the binary representation of the denary number 47?
• A) 101111₂
• B) 101011₂
,Page 2 of 64
• C) 111101₂
• D) 110111₂
Answer: A) 101111₂
Rationale: 47 = 32 + 8 + 4 + 2 + 1 = 101111₂.
3. What is the denary value of the binary number 101101₂?
• A) 45
• B) 46
• C) 53
• D) 54
Answer: A) 45
Rationale: 101101₂ = 32 + 8 + 4 + 1 = 45.
4. What is the hexadecimal representation of the binary number 101101₂?
• A) 2D
• B) 2E
• C) 3D
• D) 4D
Answer: A) 2D
Rationale: 101101₂ = 0010 1101₂ = 2D₁₆.
5. What is the denary value of the hexadecimal number 3A?
• A) 58
• B) 59
• C) 60
• D) 61
,Page 3 of 64
Answer: A) 58
Rationale: 3A₁₆ = 3 × 16 + 10 = 58.
6. What is the maximum value that can be stored in an 8-bit unsigned binary number?
• A) 127
• B) 255
• C) 256
• D) 511
Answer: B) 255
Rationale: 8 bits can store values from 0 to 2⁸ − 1 = 255.
7. What is the range of values that can be represented in 8-bit two's complement?
• A) 0 to 255
• B) −128 to +127
• C) −127 to +127
• D) −255 to +255
Answer: B) −128 to +127
Rationale: 8-bit two's complement ranges from −128 to +127.
8. Convert −25 to 8-bit two's complement binary.
• A) 11100111₂
• B) 11100110₂
• C) 11101001₂
• D) 11101000₂
Answer: A) 11100111₂
Rationale: +25 = 00011001₂. Invert to 11100110₂, add 1 → 11100111₂.
, Page 4 of 64
9. What is the denary value of the 8-bit two's complement number 11101000₂?
• A) −24
• B) −23
• C) −25
• D) −26
Answer: A) −24
Rationale: 11101000₂ = −128 + 64 + 32 + 8 = −24.
10. What is the binary representation of the denary number 0.75 using fixed point with 4
fractional bits?
• A) 0.1100₂
• B) 0.1010₂
• C) 0.1110₂
• D) 0.1001₂
Answer: A) 0.1100₂
Rationale: 0.75 = 1/2 + 1/4 = 0.11₂ = 0.1100₂.
11. What is the main advantage of floating point representation over fixed point?
• A) It can represent a wider range of values
• B) It is always more accurate
• C) It uses less memory
• D) It is faster
Answer: A) It can represent a wider range of values
Rationale: Floating point allows representation of very large and very small numbers.
AQA A-LEVEL COMPUTER SCIENCE PAPER 2 EXAM
QUESTIONS WITH VERIFIED QUESTIONS DETAILED
RATIONALES GRADED A+
AQA A-LEVEL COMPUTER SCIENCE PAPER 2
Original Questions with Answers and Rationales
SECTION 1: FUNDAMENTALS OF DATA REPRESENTATION
Questions 1–30
1. How many bits are in a byte?
• A) 4
• B) 8
• C) 16
• D) 32
Answer: B) 8
Rationale: A byte consists of 8 bits.
2. What is the binary representation of the denary number 47?
• A) 101111₂
• B) 101011₂
,Page 2 of 64
• C) 111101₂
• D) 110111₂
Answer: A) 101111₂
Rationale: 47 = 32 + 8 + 4 + 2 + 1 = 101111₂.
3. What is the denary value of the binary number 101101₂?
• A) 45
• B) 46
• C) 53
• D) 54
Answer: A) 45
Rationale: 101101₂ = 32 + 8 + 4 + 1 = 45.
4. What is the hexadecimal representation of the binary number 101101₂?
• A) 2D
• B) 2E
• C) 3D
• D) 4D
Answer: A) 2D
Rationale: 101101₂ = 0010 1101₂ = 2D₁₆.
5. What is the denary value of the hexadecimal number 3A?
• A) 58
• B) 59
• C) 60
• D) 61
,Page 3 of 64
Answer: A) 58
Rationale: 3A₁₆ = 3 × 16 + 10 = 58.
6. What is the maximum value that can be stored in an 8-bit unsigned binary number?
• A) 127
• B) 255
• C) 256
• D) 511
Answer: B) 255
Rationale: 8 bits can store values from 0 to 2⁸ − 1 = 255.
7. What is the range of values that can be represented in 8-bit two's complement?
• A) 0 to 255
• B) −128 to +127
• C) −127 to +127
• D) −255 to +255
Answer: B) −128 to +127
Rationale: 8-bit two's complement ranges from −128 to +127.
8. Convert −25 to 8-bit two's complement binary.
• A) 11100111₂
• B) 11100110₂
• C) 11101001₂
• D) 11101000₂
Answer: A) 11100111₂
Rationale: +25 = 00011001₂. Invert to 11100110₂, add 1 → 11100111₂.
, Page 4 of 64
9. What is the denary value of the 8-bit two's complement number 11101000₂?
• A) −24
• B) −23
• C) −25
• D) −26
Answer: A) −24
Rationale: 11101000₂ = −128 + 64 + 32 + 8 = −24.
10. What is the binary representation of the denary number 0.75 using fixed point with 4
fractional bits?
• A) 0.1100₂
• B) 0.1010₂
• C) 0.1110₂
• D) 0.1001₂
Answer: A) 0.1100₂
Rationale: 0.75 = 1/2 + 1/4 = 0.11₂ = 0.1100₂.
11. What is the main advantage of floating point representation over fixed point?
• A) It can represent a wider range of values
• B) It is always more accurate
• C) It uses less memory
• D) It is faster
Answer: A) It can represent a wider range of values
Rationale: Floating point allows representation of very large and very small numbers.
