An organic compound $A$ on heating with concentrated $H_2SO_4$ forms a compound $B$, which on addition of one mole of hydrogen in the presence of $Ni$ forms a compound $C$. One mole of compound $C$ on combustion forms two moles of $CO_2$ and $3$ moles of $H_2O$. Identify the compounds $A$, $B$, and $C$ and write the chemical equations of the reactions involved.

(A) Since one mole of compound $C$ gives $2$ moles of $CO_2$ and $3$ moles of $H_2O$, its molecular formula is $C_2H_6$ (Ethane).
Compound $C$ is obtained by the hydrogenation of compound $B$, so $B$ must be $C_2H_4$ (Ethene).
Compound $B$ is formed by the dehydration of compound $A$ using concentrated $H_2SO_4$, which indicates $A$ is an alcohol, specifically $C_2H_5OH$ (Ethanol).
Reaction $1$: $C_2H_5OH \xrightarrow{\text{Hot conc. } H_2SO_4} C_2H_4 + H_2O$
Reaction $2$: $C_2H_4 + H_2 \xrightarrow{Ni} C_2H_6$
Reaction $3$: $2C_2H_6 + 7O_2 \to 4CO_2 + 6H_2O + \text{Heat and light}$