$A$ spontaneous process is impossible if ........

The free energy for a reaction having $\Delta H = 31400 \, cal$ and $\Delta S = 32 \, cal \, K^{-1} \, mol^{-1}$ at $1000 \, ^oC$ is ....... $cal$.

For a reaction,$\Delta H = -40 \, kJ$ and $\Delta S = -50 \, J/K$. At what temperature range will it change from spontaneous to non-spontaneous?

For a reaction,$4 M (s) + n O_2 (g) \rightarrow 2 M_2 O_n (s)$,the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which :

For the decomposition reaction of $N_2O_4$,$\Delta H = 58.04 \, kJ$ and $\Delta S = 176.7 \, J/K$. Calculate $\Delta G$ in $kJ$ at $T = 298 \, K$.

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