$2$-Hexyne reacts with $.......$ to give $trans-2$-hexene.

What are $X$ and $Y$ respectively in the following reaction?
$Z$-product $\stackrel{Y}{\longleftarrow} 2$-butyne $\stackrel{X}{\longrightarrow} E$-product

An unknown compound $X$ is an unsaturated hydrocarbon. It reacts with $HgSO_4$ and $H_2SO_4$ to give compound $(B)$. Compound $(B)$ on oxidation gives compound $(C)$. Compound $(C)$ on reaction with $NaOH$ and soda lime gives methane. Identify $A$ (which is $X$),$B$,and $C$ by providing the chemical reactions.

Which gas is used in metal welding?

Acetylene reacts with a $42\% H_2SO_4$ solution containing $1\% HgSO_4$ to give

The product $(B)$ is: