$3)$ Given the following data NH$3($g$)->1/2$ N$2($g$)+3/2$ H$2($g$)\backslash$Delta H$=46$ kJ $2$H$2($g$)+$ O$2($g$)->2$H$2$O$($g$)\backslash$Delta H$=-484$ kJ calculate $\backslash$Delta H for the reaction $2$N$2($g$)+6$H$2$O$($g$)->3$O$2($g$)+4$NH$3($g$)$ On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?