Acetylene reacts with dilute $H_2SO_4$ in the presence of $HgSO_4$ to produce .......

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:

What is the increasing order of acidity for the following substances?
$(1)$ $CH_2=CH_2$
$(2)$ $CH_3-CH_3$
$(3)$ $HC \equiv CH$
$(4)$ $NH_3$

The product obtained in this reaction is:

$CH_3 - CH_2 - C \equiv CH \xrightarrow{HgSO_4, H_2SO_4} A$,the compound $A$ is

Ethene can be separated from acetylene by passing the mixture through :