The work done when 2 moles of an ideal gas expands rèversibly and isothermally from a volume of $$1 \mathrm{~L}$$ to $$10 \mathrm{~L}$$ at $$300 \mathrm{~K}$$ is ($$R=0.0083 \mathrm{~kJ} \mathrm{~K} \mathrm{~mol}^{-1}$$)

When the same quantity of heat is absorbed by a system at two different temperatures $$T_1$$ and $$T_2$$, such that $$T_1>T_2$$, change in entropies are $$\Delta S_1$$ and $$\Delta S_2$$ respectively. Then

The reaction in which $$\Delta H=\Delta U$$ is