Identify from following reactions that exhibits negative work done.

Calculate the enthalpy of solution of potassium chloride if its $\Delta_{\mathrm{L}} \mathrm{H}=700 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta_{\text {hyd }} H=-680 \mathrm{~kJ} \mathrm{~mol}^{-1}$

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 .