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.

(N/A) The reaction sequence is as follows:
$1$. $HC \equiv CH$ (Ethyne,$A$) reacts with $HgSO_4 / H_2SO_4$ to form $CH_3CHO$ (Ethanal,$B$).
$2$. $CH_3CHO$ (Ethanal,$B$) on oxidation (using $KMnO_4$) gives $CH_3COOH$ (Ethanoic acid,$C$).
$3$. $CH_3COOH$ (Ethanoic acid,$C$) reacts with $NaOH$ to form $CH_3COONa$ (Sodium ethanoate),which on heating with soda lime $(NaOH + CaO)$ gives $CH_4$ (Methane).
Thus,$A = HC \equiv CH$ (Ethyne),$B = CH_3CHO$ (Ethanal),and $C = CH_3COOH$ (Ethanoic acid).