The reaction,

The reaction,

$\mathrm{MgO}(\mathrm{s})+\mathrm{C}(\mathrm{s}) \rightarrow \mathrm{Mg}(\mathrm{S})+\mathrm{CO}(\mathrm{g})$, for which $\Delta_{\mathrm{r}} \mathrm{H}^{\circ}$ $=+491.1 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta_{\mathrm{r}} \mathrm{S}^{\circ}=198.0 \mathrm{JK}^{-1} \mathrm{~mol}^{-}$ 1 , is not feasible at $298 \mathrm{~K}$. Temperature above which reaction will be feasible is :-