Question

Acidic hydrogen is present in

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

Answer 1

Answer: (A)

ethyne

Answer 2

Terminal alkynes are slightly acidic, forms salt with very strong base like Na, $NaNH_2$ etc.
$\, \, \, \, \, H-C\equiv C-H+Na \xrightarrow{\, \, \Delta \, \, \, } H- C \equiv C^- Na^+ + \frac{1}{2}H^2 \uparrow$