Question

The most acidic hydrogen atoms are present in:

• A. ethane
• B. ethene
• C. ethyne
• D. benzene

Answer 1

Answer: (C)

ethyne

The acidity of hydrogen atoms is directly proportional to the presence of s-character.

Compound	Chemical Formula	Hybridisation	$\%$ s-character
Ethane	$C{H}_3-C{H}_3$	$s{p}^3$	$25\%$
Ethene	$C{H}_2=C{H}_2$	$s{p}^2$	$33.33\%$
Ethyne	$CH\equiv CH$	$sp$	$50\%$
Benzene	$C_6{H}_6$	$s{p}^2$	$33.33\%$

Since, Ethyne has highest percentage of s-character, hence, most acidic hydrogen atoms are present in ethyne.