The criterion for a spontaneous process is

For the given reaction: $H_{2(g)} + S_{(s)} \to H_2S_{(g)}$; $\Delta H_r = 100\, kJ/mol$ and $\Delta S_r = 400\, J/mol\cdot K$. The temperature at which the above reaction occurs reversibly is (Assuming $\Delta H_r$ and $\Delta S_r$ are independent of temperature) ..... $K$.

For a spontaneous process,which of the following conditions must be met?

The standard enthalpy of the decomposition of $N_2O_4$ 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 $..... \, kJ$

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

Which of the following reactions is expected to never be spontaneous?