What is formed when calcium carbide reacts with heavy water?

The relation between $(B)$ and $(C)$ is:
$CH_3-C \equiv CH$ $\xrightarrow{NaNH_2}$ $\xrightarrow{CH_3-I} (A)$ $\xrightarrow{Li/liq. NH_3} (B)$
$CH_3-C \equiv CH$ $\xrightarrow{NaNH_2}$ $\xrightarrow{CH_3-I} (A)$ $\xrightarrow[Pd/CaCO_3]{H_2} (C)$

The major product in the following reaction is $H_3C-C\equiv CH + HBr$ (excess)

In the following reaction,compound $A$ is formed,which reacts with $B$ to give product $C$. Identify $A$ and $B$.

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

$1, 2$-Dibromopropane on treatment with $X$ moles of $NaNH_2$ followed by reaction with ethyl bromide gives $2$-pentyne. The value of $X$ is: