Which of the following statements are correct? Select all that apply.

AEthyne reacts with aqueous NaOH to give sodium acetylide almost completely
BThe acidity order is $HC \equiv CH > CH X_{2} = CH X_{2} > CH X_{3} CH X_{3}$ because of the increasing s-character of the carbon orbital in the C-H bond
CSodium acetylide is hydrolysed by water to give ethyne
DThe acetylide ion $HC \equiv C X^{-}$ is a stronger base than $OH X^{-}$

Answer: B, C, D

A larger s-character stabilises the carbanion, giving the acidity order ethyne > ethene > ethane. The conjugate acid of acetylide (ethyne,

p K_{a} \approx 25

) is weaker than water (15.7), so acetylide is the stronger base and is protonated by water, regenerating ethyne. For the same reason aqueous NaOH cannot convert ethyne to its anion to any significant extent.

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Which of the following statements are correct? Select all that apply.

Answer: B, C, D

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