In conversion of limestone to lime, <br> $CaCO_3 (s) \to CaO(s) + CO_2(g)$ <br> the values of $\Delta H^{\circ}$ and $\Delta S^{\circ}$ are $+179.1\;kJ\; mol^{-1}$ and $160.2\;J/K$ respectively at 298 K and 1 bar. Assuming that $\Delta H^{\circ}$ and $\Delta S^{\circ}$ do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is :