What is the value of standard enthalpy of formation of dihydrogen?

Calculate Gibbs energy change for a reaction having $\Delta \mathrm{H}=31400 \mathrm{~J}, \Delta \mathrm{~S}=32 \mathrm{~J} \mathrm{~K}^{-1}$ at $1000^{\circ} \mathrm{C}$ ?

If 100 L gas is enclosed in a cylinder, absorbs 302.6 J of heat and expands to 200 L against constant external pressure of 2 atm . Calculate internal energy change of the gas.

Which of the following is true for the value of $\Delta \mathrm{H}-\Delta \mathrm{U}$ at constant volume?