A system performs mechanical work equal to 15 kJ and looses 2 kJ of heat to surrounding. What is the change in internal energy of a system?

Find the constant external pressure required to expand a gas from 2.5 L to 4.5 L if amount of work done is 500 J at 298 K ?

In a particular reaction ' x ' kJ of heat is released by the system and ' y ' kJ of work done is done on the system. What is internal energy change?

Calculate the value of $\Delta G$ for the following reaction. $\mathrm{N}_2 \mathrm{O}_{4(\mathrm{~g})} \longrightarrow 2 \mathrm{NO}_{2(\mathrm{~g})}$ if $\Delta \mathrm{H}=57.44 \mathrm{~kJ}$ and $\Delta \mathrm{S}=176 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$.