When acetylene is passed into dilute sulphuric acid containing $Hg^{2+}$ ions,the product formed is

Write the following reactions:
$(1)$ Reaction of acetylene with $HCN$.
$(2)$ Hydrogenation of ethyne in the presence of Lindlar catalyst $(Pd, BaSO_4)$.

$HC \equiv CH$ $\xrightarrow[{excess}]{{CH_3MgBr}} \mathop {(A)}\limits_{\text{salt}} + \mathop {(B)}\limits_{\text{hydrocarbon}}$
$(A)$ $\xrightarrow[{excess}]{{CH_3I}} (C)$ $\xrightarrow[{(ii) H^{+} }]{{(i) NaNH_2}} (D)$

What will be obtained by the reaction of calcium carbide with heavy water? Give its chemical equation.

Which hydrocarbon reacts with sodium in liquid ammonia?

Identify the alkyne in the following sequence of reactions: