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Data Representation & Abstraction

Topic in Problem Solving & Analytical Skills

210 total MCQsShowing 30 with explanations10 Easy10 Medium10 Hard
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Data representation is how numbers, text and relationships are encoded for a computer, while abstraction hides those details behind simpler interfaces. Typical questions convert between decimal, binary, octal and hexadecimal (grouping bits in threes for octal and fours for hex), explain two's complement, ASCII and Unicode, and define variables and data types. Many items compare abstract data types and structures: arrays, linked lists, stacks, queues, priority queues, trees, graphs and hash tables. More advanced ones ask why B-trees suit disk-based databases and how a Bloom filter tests set membership with possible false positives but no false negatives.

Below are 30 practice questions from a pool of 210 Data Representation & Abstraction MCQs, one of 16 topics in Problem Solving & Analytical Skills. Each shows the correct answer with an explanation; when you are ready, take a timed quiz to test recall under exam conditions.

Practice Questions

Each question below shows the correct answer with a full explanation. Use these to build conceptual understanding before attempting a timed quiz.

Data Representation & AbstractionEasy

Q1. Binary of decimal 5?

  1. A.110
  2. B.111
  3. C.101✓ Correct
  4. D.100

Explanation

101 is the correct answer to this question.

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Data Representation & AbstractionEasy

Q2. What is abstraction in data?

  1. A.Making things increasingly complex
  2. B.Showing all implementation details
  3. C.Deleting all the stored data
  4. D.Hiding unnecessary, showing essential✓ Correct

Explanation

Hides unnecessary details.

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Data Representation & AbstractionEasy

Q4. Data type for name?

  1. A.String✓ Correct
  2. B.Boolean
  3. C.Float
  4. D.Integer

Explanation

String for text.

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Data Representation & AbstractionEasy

Q5. What is an array?

  1. A.A specific type of loop construct
  2. B.A callable function definition
  3. C.A single variable only
  4. D.Same-type elements in contiguous memory✓ Correct

Explanation

Contiguous same-type elements.

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Data Representation & AbstractionEasy

Q6. What does ASCII stand for?

  1. A.Automated Standard Code for Input Interfacing
  2. B.American Standard Code for Information Interchange✓ Correct
  3. C.American System for Computer Information Indexing
  4. D.Advanced System Code for Internet Integration

Explanation

American Standard Code for Information Interchange.

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Data Representation & AbstractionEasy

Q7. Decimal of binary 1010?

  1. A.12
  2. B.10✓ Correct
  3. C.8
  4. D.14

Explanation

10 is the correct answer to this question.

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Data Representation & AbstractionEasy

Q8. Which uses key-value pairs?

  1. A.Dictionary/Map✓ Correct
  2. B.Array structure
  3. C.Queue structure
  4. D.Stack structure

Explanation

Dictionaries store key-value pairs.

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Data Representation & AbstractionEasy

Q9. What is Boolean?

  1. A.String text type
  2. B.Decimal number type
  3. C.Only true or false✓ Correct
  4. D.Float number type

Explanation

Two values: true/false.

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Data Representation & AbstractionEasy

Q10. What is hexadecimal?

  1. A.Base-8 system
  2. B.Base-2 system
  3. C.Base-10 system
  4. D.Base-16 system✓ Correct

Explanation

Base-16 number system.

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Data Representation & AbstractionMedium

Q11. Hex of 255?

  1. A.1F
  2. B.FE
  3. C.EF
  4. D.FF✓ Correct

Explanation

FF is the correct answer to this question.

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Data Representation & AbstractionMedium

Q12. Two's complement is for?

  1. A.Floating point values
  2. B.Signed integers in binary✓ Correct
  3. C.Data compression formats
  4. D.Text character encoding

Explanation

Represents signed integers.

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Data Representation & AbstractionMedium

Q13. 8-bit two's complement of -1?

  1. A.00000001
  2. B.10000001
  3. C.11111110
  4. D.11111111✓ Correct

Explanation

11111111 is the correct answer to this question.

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Data Representation & AbstractionMedium

Q14. Data abstraction in OOP?

  1. A.Hide implementation, expose interface✓ Correct
  2. B.Write longer and more verbose code
  3. C.Expose all internal details fully
  4. D.Avoid using functions or methods

Explanation

Hides behind public interface.

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Data Representation & AbstractionMedium

Q15. ADT vs data structure?

  1. A.Data structure is always better to use
  2. B.ADT: interface; structure: implementation✓ Correct
  3. C.ADT can never be implemented in code
  4. D.They are exactly the same thing

Explanation

ADT = what; structure = how.

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Data Representation & AbstractionMedium

Q16. IEEE 754 representation?

  1. A.Character encoding standard
  2. B.Sign, exponent, and mantissa✓ Correct
  3. C.Only the mantissa component
  4. D.Simple integer format only

Explanation

Three components: sign, exponent, mantissa.

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Data Representation & AbstractionMedium

Q17. Unicode vs ASCII?

  1. A.Unicode only supports English letters
  2. B.They are exactly the same standard
  3. C.ASCII has more characters than Unicode
  4. D.Unicode: all scripts; ASCII: 128 chars✓ Correct

Explanation

Unicode is universal; ASCII is limited.

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Data Representation & AbstractionMedium

Q18. What is a struct?

  1. A.Composite grouping different types✓ Correct
  2. B.A single primitive variable only
  3. C.A file format for data storage
  4. D.A database table definition format

Explanation

Groups related fields.

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Data Representation & AbstractionMedium

Q19. What is serialization?

  1. A.Encrypting sensitive data
  2. B.Deleting data permanently
  3. C.Converting to storable format✓ Correct
  4. D.Sorting data in an order

Explanation

Converts data for storage/transmission.

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Data Representation & AbstractionMedium

Q20. Unsigned 8-bit range?

  1. A.1-256
  2. B.0-127
  3. C.-128 to 127
  4. D.0-255✓ Correct

Explanation

0-255 is the correct answer to this question.

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Data Representation & AbstractionHard

Q21. Float problems vs integer?

  1. A.Rounding errors only
  2. B.Overflow errors only
  3. C.All of the above✓ Correct
  4. D.Underflow errors only

Explanation

All three can occur.

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Data Representation & AbstractionHard

Q22. What is endianness?

  1. A.A sorting algorithm technique
  2. B.A programming paradigm style
  3. C.A data compression approach
  4. D.Byte order stored in memory✓ Correct

Explanation

Byte storage order.

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Data Representation & AbstractionHard

Q23. IEEE 754 single exponent bits?

  1. A.32 bits
  2. B.23 bits
  3. C.8 bits✓ Correct
  4. D.1 bit

Explanation

1+8+23 = 32 bits.

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Data Representation & AbstractionHard

Q24. What is a tagged union?

  1. A.An array with mixed types
  2. B.A union with a type tag field✓ Correct
  3. C.A regular union without tags
  4. D.A sorting data structure type

Explanation

Includes type discriminator.

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Data Representation & AbstractionHard

Q25. What is information hiding?

  1. A.Encrypting all data in storage
  2. B.Deleting data after processing
  3. C.Hiding files on the filesystem
  4. D.Restricting access, exposing interfaces✓ Correct

Explanation

Exposes only necessary interfaces.

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Data Representation & AbstractionHard

Q26. What is data alignment?

  1. A.Alphabetical sorting of records
  2. B.Formatting text in a document
  3. C.Aligning elements on the screen
  4. D.Placing at boundaries for CPU access✓ Correct

Explanation

Efficient CPU memory access.

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Data Representation & AbstractionHard

Q27. What is Liskov Substitution Principle?

  1. A.Subtypes substitutable for supertypes✓ Correct
  2. B.Making all class members public
  3. C.An encryption standard for data
  4. D.Functions without any parameters

Explanation

Subtypes must be substitutable.

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Data Representation & AbstractionHard

Q28. What is a phantom type?

  1. A.A null type with no useful value
  2. B.A runtime type for dynamic checks
  3. C.Type param with compile-time info only✓ Correct
  4. D.A type that does not exist at all

Explanation

Compile-time info without runtime presence.

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Data Representation & AbstractionHard

Q29. IEEE 754 single max value?

  1. A.3.4e38✓ Correct
  2. B.2^64
  3. C.1.8e308
  4. D.2^31

Explanation

Approximately 3.4 x 10^38.

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Data Representation & AbstractionHard

Q30. Structural vs nominal typing?

  1. A.They are exactly the same thing
  2. B.Nominal typing is not used in practice
  3. C.Structural is always better to use here
  4. D.Structural: shape match; nominal: name match✓ Correct

Explanation

Structure compatibility vs name compatibility.

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