Question

give 2 reactions to show acidic charcter of alkynes

Answer 1

The most common reaction to show the acidic character of alkyne is reaction with strong base like NaNH2 to form Na salt of alkyne as shown below:
H-C≡C-H   +   NaNH2  (in ammonia or ether)  ——>  H-C≡C-Na (sodium acetylide)   +   NH3
​The other example is reaction of alkyne with grignard reagent as shown below:
 RC≡C-H   +   C2H5MgBr   (in ether)  ——>  RC≡C-MgBr