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NEET levelSingle correct optionDifficulty 1 of 3hc113

Which is the correct order of acidic strength of the C-H bond?

A $HC \equiv CH > H X_{2} C = CH X_{2} > CH X_{3} - CH X_{3}$
B $CH X_{3} - CH X_{3} > H X_{2} C = CH X_{2} > HC \equiv CH$
C $CH X_{3} - CH X_{3} > HC \equiv CH > H X_{2} C = CH X_{2}$
D $H X_{2} C = CH X_{2} > HC \equiv CH > CH X_{3} - CH X_{3}$

Answer: A

Acidity follows the s-character of the carbon bearing the hydrogen, which stabilises the carbanion: sp (50%) in ethyne,

sp X_{2}

(33%) in ethene and

sp X_{3}

(25%) in ethane. Hence ethyne > ethene > ethane.

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