Calculate the standard enthalpy change for the following reaction,
$2\text{C}_2\text{H}_6\text{(g)} + 7\text{O}_2\text{(g)} \longrightarrow 4\text{CO}_2\text{(g)} + 6\text{H}_2\text{O}\text{(l)}$
Given, $\Delta_f H^\circ(\text{C}_2\text{H}_6) = -85\ \text{kJ mol}^{-1}$
$\Delta_f H^\circ(\text{CO}_2) = -390\ \text{kJ mol}^{-1}$
$\Delta_f H^\circ(\text{H}_2\text{O}) = -285\ \text{kJ mol}^{-1}$

Calculate $\Delta\text{H}$ for the following reaction at $300\ \text{K}$
$2\text{C}_{(s)} + 3\text{H}_{2(g)} \longrightarrow \text{C}_2\text{H}_{6(g)}$ if $\Delta\text{U}$ for the reaction is $-80\ \text{kJ}$ ($\text{R} = 8.314\ \text{JK}^{-1}\text{mol}^{-1}$)

For a certain reaction, $\Delta\text{H}^\circ = 40\ \text{kJ}$ and $\Delta\text{S}^\circ = 80\ \text{JK}^{-1}$. Find the temperature so that $\Delta\text{G}^\circ = 0$

Which from following is correct expression of first law of thermodynamics for isothermal process?