The simplest alkyne is represented by which of the following?

The product$(s)$ obtained via oxymercuration $(HgSO_4 + H_2SO_4)$ of $1$-butyne would be:

Which is the most acidic of the following?

$C_2H_2$ $\xrightarrow{\text{dil. } H_2SO_4, HgSO_4} A$ $\xrightarrow{[O]} B$ $\xrightarrow{NaOH} C$ $\xrightarrow{NaOH/CaO} D$
$[D]$ is -

The treatment of $CH_3MgX$ with $CH_3-C \equiv CH$ produces

Provide the chemical reactions for the following conversions:
$(1)$ Propyne from ethyne
$(2)$ $2-$butyne and $1-$butyne from ethyne