For a process occurring at constant temperature and pressure,which of the following is true at equilibrium?

$A$ chemical reaction cannot occur at all if

The relation $\Delta G = \Delta H - T\Delta S$ was given by

If a chemical reaction is known to be non-spontaneous at $298 \ K$ but spontaneous at $350 \ K$,then which among the following conditions is true for the reaction?

Calculate $\Delta H_f^o$ for $UBr_4$ from the $\Delta G^o$ of reaction and the $S^o$ values: $U_{(s)} + 2Br_2(\ell) \to UBr_{4(s)}$; $\Delta G^o = -788.6 \ kJ$; $S^o \ (J/K \cdot mol): U_{(s)} = 50.3, Br_2(\ell) = 152.3, UBr_{4(s)} = 242.6$.

For the conversion of limestone to lime,$CaCO_{3(s)} \rightarrow CaO_{(s)} + CO_{2(g)}$,the values of $\Delta H^{\circ}$ and $\Delta S^{\circ}$ at $298 \, K$ and $1 \, bar$ pressure are $+179.1 \, kJ \, mol^{-1}$ and $160.2 \, J \, K^{-1} \, mol^{-1}$ respectively. Assuming $\Delta H^{\circ}$ and $\Delta S^{\circ}$ do not change with temperature,at what temperature (in $K$) will the conversion of limestone to lime become spontaneous (in $, K$)?