Which of the following would be produced when acetylene reacts with $HCl$?

Which of the following compounds is capable of reacting with ammoniacal $AgNO_3$ solution?

The isomerisation of $1-$butyne to $2-$butyne can be achieved by treatment with

Identify the product $D$ in the following series of reaction: $CH_3COOH$ $\xrightarrow{LiAlH_4} A$ $\xrightarrow{H^{+}, 443 \ K} B$ $\xrightarrow{Br_2} C$ $\xrightarrow{alc. KOH} D$

In the following reaction:
$C_2H_2$ $\xrightarrow[HgSO_4 / H_2SO_4]{H_2O} (x)$ $\xrightarrow{\text{Tautomerisation}} CH_3-CHO$
$(x)$ is $:-$

Number of acidic hydrogen atoms in $but-1-yne$ are