Under what conditions does a reaction always occur spontaneously?

State the criteria for a spontaneous process in terms of $\Delta G$ at constant pressure and temperature.

The condition for a reaction to occur spontaneously is

The standard enthalpy for the decomposition of $N_2O_5$ to $NO_2$ is $58.04 \ kJ$ and standard entropy of this reaction is $176.7 \ J/K$. The standard free energy change for this reaction at $25 \ ^oC$ is .................. $kJ$.

For a chemical reaction,if $\Delta H > 0$ and $\Delta S > 0$,under what condition will the reaction not be spontaneous?

At what temperature $(T \ K)$ will the reaction be in equilibrium (in $K$)? $Ag_2O_{(s)} \rightarrow 2Ag_{(s)} + \frac{1}{2} O_{2(g)}$,given $\Delta H = 30.5 \ kJ \ mol^{-1}$ and $\Delta S = 0.066 \ kJ \ K^{-1} \ mol^{-1}$.