$A$ mixture of ethane,ethene,and ethyne is passed through ammoniacal $AgNO_3$ solution. The gases which remain unreacted are

When acetylene reacts with arsenic trichloride in the presence of anhydrous aluminium chloride,it produces

$A$ hydrocarbon $X$ with molecular formula $C_4H_6$ decolourises bromine water and forms a white precipitate in ethanolic $AgNO_3$ solution. Treatment of $X$ with $HgCl_2$ in aqueous $H_2SO_4$ produces a compound,which gives a yellow precipitate when treated with $I_2$ and $NaOH$. The structure of $X$ is

The synthesis of $3-$octyne is achieved by adding a bromoalkane into a mixture of sodium amide and an alkyne. The bromoalkane and alkyne respectively are

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.

Hydrogenation of $2-$Butyne in the presence of Lindlar's catalyst gives