Base Class Library interview questions

18 real Base Class Library questions from the .NET bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is Base Class Library?

Junior
  1. A.the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
  2. B.the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  3. C.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  4. D.the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
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3. Which statement is correct?

Junior
  1. A.Base Class Library — the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  2. B.Base Class Library — a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  3. C.Base Class Library — the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
  4. D.Base Class Library — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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4. What is Generic collections?

Junior
  1. A.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  2. B.the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  3. C.the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  4. D.the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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5. Which term means: "the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting"?

Junior
  1. A.Generic collections
  2. B.System.Text.Json
  3. C.HttpClient
  4. D.Base Class Library
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6. Which statement is correct?

Junior
  1. A.Generic collections — the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
  2. B.Generic collections — the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  3. C.Generic collections — the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  4. D.Generic collections — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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7. What is System.Text.Json?

Mid
  1. A.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  2. B.the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  3. C.the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
  4. D.the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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8. Which term means: "the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults"?

Mid
  1. A.System.Text.Json
  2. B.Memory of T
  3. C.Base Class Library
  4. D.Generic collections
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9. Which statement is correct?

Mid
  1. A.System.Text.Json — a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  2. B.System.Text.Json — the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  3. C.System.Text.Json — the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
  4. D.System.Text.Json — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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10. What is HttpClient?

Mid
  1. A.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  2. B.the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  3. C.the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
  4. D.the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
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11. Which term means: "the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call"?

Mid
  1. A.Memory of T
  2. B.Span of T
  3. C.Generic collections
  4. D.HttpClient
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12. Which statement is correct?

Mid
  1. A.HttpClient — the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  2. B.HttpClient — a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  3. C.HttpClient — a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  4. D.HttpClient — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
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13. What is Span of T?

Senior
  1. A.the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
  2. B.a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  3. C.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  4. D.the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
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14. Which term means: "a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying"?

Senior
  1. A.Span of T
  2. B.System.Text.Json
  3. C.Generic collections
  4. D.Memory of T
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15. Which statement is correct?

Senior
  1. A.Span of T — the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
  2. B.Span of T — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
  3. C.Span of T — a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  4. D.Span of T — the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
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16. What is Memory of T?

Senior
  1. A.the foundational set of types shipped with the platform covering collections, I/O, text, networking and more
  2. B.a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  3. C.the namespace of strongly typed containers such as lists, dictionaries and queues that avoid boxing and casting
  4. D.the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
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17. Which term means: "a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live"?

Senior
  1. A.Memory of T
  2. B.HttpClient
  3. C.Generic collections
  4. D.System.Text.Json
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18. Which statement is correct?

Senior
  1. A.Memory of T — a stack-only value type giving a bounds-checked window over contiguous memory such as arrays or slices without copying
  2. B.Memory of T — a heap-storable counterpart to the stack-only window type, usable in asynchronous methods where the restricted type cannot live
  3. C.Memory of T — the primary type for sending requests and receiving responses over HTTP, designed to be reused rather than created per call
  4. D.Memory of T — the built-in, high-performance serializer for reading and writing JavaScript Object Notation, replacing older third-party defaults
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