Addition of $HCN$ to ethyne in the presence of $Ba(CN)_2$ as a catalyst gives:

By heating a mixture of $CHCl_3$ with silver powder,the compound formed is

$\underset{(\text{Calcium carbide})}{CaC_2}$ $\xrightarrow{H_2O} (A)$ $\xrightarrow{\text{Red hot Cu tube}} (B)$. The product $(B)$ of the reaction is:

The end product of the following sequence is
$CaC_2$ $\xrightarrow{H_2O} B$ $\xrightarrow[HgSO_4]{H_2O, H_2SO_4} C$

$C_6H_5-C \equiv C-CH_3 \xrightarrow[H_2SO_4]{HgSO_4, H_2O} A$. The major product $(A)$ is:

What is formed when calcium carbide reacts with heavy water?