The number of $\sigma$ and $\pi$ bonds present in $pent-4-en-1-yne$ is

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

The final product of the following reaction is .......
$CaO + 3C$ $\xrightarrow{\text{Heat}} A$ $\xrightarrow{H_2O} B$ $\xrightarrow{H_2SO_4, Hg^{2+}} C$

Benzene is the polymer of

Which is the most suitable reagent among the following to distinguish compound $(iii)$ from the rest of the compounds?
$(i)$ $CH_3-C\equiv C-CH_3$
$(ii)$ $CH_3-CH_2-CH_2-CH_3$
$(iii)$ $CH_3-CH_2-C\equiv CH$
$(iv)$ $CH_3-CH=CH_2$

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