Calculate the change in internal energy of the system if 20 kJ work is done on the system and it releases 10 kJ heat in a particular reaction.

Calculate the work done in joule if 2 moles of an ideal gas expand isothermally from $15.5 \mathrm{dm}^3$ to $20 \mathrm{dm}^3$ at constant pressure 1 atm .

1.8 g water is vapourised by supplying 4 kJ heat at $100^{\circ} \mathrm{C}$. What is the heat of vapourisation of water at same temperature?

Calculate the standard enthalpy change of following reaction

$$ \begin{aligned} & \mathrm{CH}_{4(\mathrm{~g})}+2 \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{CO}_{2(\mathrm{~g})}+2 \mathrm{H}_2 \mathrm{O}_{(\ell)} \\ & \text { If } \Delta_{\mathrm{f}} \mathrm{H}^{\circ}\left(\mathrm{CH}_4\right)=-75 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ & \Delta_{\mathrm{f}} \mathrm{H}^{\circ}\left(\mathrm{CO}_2\right)=-394 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ & \Delta_{\mathrm{f}} \mathrm{H}^{\circ}\left(\mathrm{H}_2 \mathrm{O}\right)=-286 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{aligned} $$