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Question 770003
JEE Chemistry · Easy

Hydrocarbons: Alkyne acidity MCQ

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Alkyne acidityEasyQuestion 770003

Question

Terminal alkynes (RC≡CH) are more acidic than alkanes because:
  1. A
    sp-hybridised C has more s-character, holding electrons closer to nucleus, stabilising carbanion
    Correct
  2. B
    Triple bonds attract protons
  3. C
    They are larger
  4. D
    They are linear

Correct answer

sp-hybridised C has more s-character, holding electrons closer to nucleus, stabilising carbanion

Explanation

sp carbon has 50% s-character (vs sp² = 33%, sp³ = 25%). More s-character → electrons held closer to nucleus → more electronegative C → more stable carbanion → more acidic C−H bond. pKa: alkyne (25) < alkene (44) < alkane (50).

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