Which of the following compounds forms a $Na$-salt upon reaction with $NaNH_2$?

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

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:

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

$CH_3-CH_2-CH_2-C \equiv CH \xrightarrow[\text{Excess}]{HCl} ?$

When calcium carbide is reacted with heavy water,which of the following product$(s)$ will be formed?
$I$. $CD_4$
$II$. $C_2D_2$
$III$. $Ca(OD)_2$
$IV$. $Ca_2 \cdot D_2O$