The hydrogen atoms present in acetylene molecule are :

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acidic

basic

both acidic and basic

neutral

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Answer is Wrong!

This question was previously asked in

UPSC CAPF – 2015

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Acetylene has the chemical formula C₂H₂ and a linear structure H-C≡C-H. The carbon atoms in acetylene are sp hybridized. sp hybridized orbitals have higher s-character (50%) compared to sp² (33.3%) or sp³ (25%) hybridized orbitals. Higher s-character means the electrons in the C-H bond are held more closely to the carbon nucleus due to the greater penetration of the s orbital. This makes the carbon atom more electronegative than sp² or sp³ hybridized carbons, and consequently, it pulls electron density away from the hydrogen atom. This makes the C-H bond weaker and the hydrogen slightly positive, allowing it to be removed as a proton (H⁺) by a strong base. Therefore, the hydrogen atoms in acetylene are acidic.

The acidity of terminal alkynes (like acetylene) is due to the high electronegativity of the sp-hybridized carbon atom to which the hydrogen is attached. This polarizes the C-H bond, making the proton relatively easy to remove.

Acetylene is a weak acid, much weaker than carboxylic acids or mineral acids, but significantly more acidic than alkanes or alkenes. It can react with very strong bases, such as sodium amide (NaNH₂), to form acetylide salts (e.g., Na⁺ [C≡CH]⁻ or Na⁺ [C≡C]⁻ Na⁺). This acidic property is utilized in certain organic synthesis reactions.

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