Propyne on cyclic polymerisation gives

In the following reaction:
$C_2H_2$ $\xrightarrow[HgSO_4 / H_2SO_4]{H_2O} (x)$ $\xrightarrow{\text{Tautomerisation}} CH_3-CHO$
$(x)$ is $:-$

$CH_3C \equiv C^-Na^+ + (CH_3)_2CH-Cl \to$ What will be the product of this reaction?

Which of the following reactions is not correct?

The number of $\pi$ bonds in $3$-hexyne-$1$-ene is

The following reaction is an example of a ....... reaction: $CH_2Br-CH_2Br + 2KOH (alc.) \xrightarrow{\Delta} CH \equiv CH + 2KBr + 2H_2O$