Which one of the following classes of compounds is obtained by the cyclic polymerization of acetylene?

What is the major product formed when propyne reacts with aqueous $HgSO_4$ in the presence of $H_2SO_4$?

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

Which one of the following is more acidic?

Give the reaction for the cyclization of ethyne,or the reaction for passing ethyne through a red-hot iron tube.

Propene and propyne can be distinguished by