Acetylene gives which of the following reactions?

Carbon-carbon bond length is minimum in

Given below are two statements:
Statement $I$: One mole of propyne reacts with excess of sodium to liberate half a mole of $H_2$ gas.
Statement $II$: Four $g$ of propyne reacts with $NaNH_2$ to liberate $NH_3$ gas which occupies $224 \ mL$ at $STP$.
In the light of the above statements,choose the most appropriate answer from the options given below:

$A$ salt-producing hydrocarbon among these compounds is

What is the product formed when $4$-octyne reacts with $H_2$ in the presence of $Pd/CaCO_3$?

Which reagent is used for the following transformation? $Br-CH_2-CH_2-Br \rightarrow H-C \equiv C-H$