\textbf{216-} If the standard enthalpies of combustion of ethyne and ethane are $-1298$ and $-1409$ kJ/mol respectively, and the standard enthalpy of formation of $\text{H}_2\text{O(l)}$ is $-286\ \text{kJ.mol}^{-1}$, what is the standard enthalpy of formation of ethyne and ethane in kJ/mol?
\begin{center}
(1) $111$ \hfill (2) $122$ \hfill (3) $175$ \hfill (4) $277$
\end{center}
\medskip