Calculate the enthalpy change for the following reaction, using given bond energy (kJ/mol)
(C-H = $414$, H-O = $463$, H-Cl = $431$, C-Cl = $326$ and C-O = $335$)
$\text{CH}_3\text{OH}_{(g)} + \text{HCl}_{(g)} \rightarrow \text{CH}_3\text{Cl}_{(g)} + \text{H}_2\text{O}_{(g)}$

Calculate the work done when $1$ mole of an ideal gas is expanded reversibly and isothermally from initial pressure $10$ bar to final pressure $1$ bar at constant temperature $300$ K. [$R = 8.314 \text{ J K}^{-1} \text{ mol}^{-1}$]

Which of the following processes exhibits, $\Delta U = 0$?

Calculate the work done in the oxidation of one mole $\mathrm{HCl}_{(\mathrm{g})}$ at $27^{\circ} \mathrm{C}$, according to reaction.

$$ \begin{aligned} & 4 \mathrm{HCl}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{Cl}_{2(\mathrm{~g})}+2 \mathrm{H}_2 \mathrm{O}_{(\mathrm{g})} \\ & \left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right) \end{aligned} $$