The compound belonging to the homologous series of ethyne is .........

The major product of the following reaction is $CH_3-C\equiv CH \xrightarrow[(ii) \ DI]{(i) \ DCl \ (1 \ equiv)}$

The reagent$(s)$ for the following conversion is/are:
$Br-CH_2-CH_2-Br \xrightarrow{?} HC \equiv CH$

Write structures of different isomers corresponding to the $5^{th}$ member of alkyne series. Also write $IUPAC$ names of all the isomers. What type of isomerism is exhibited by different pairs of isomers?

$1$-butyne can be distinguished from $2$-butyne by

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