The reaction of cyanamide, NH₂CN_(s) with oxygen was run in a bomb calorimeter and $\Delta U$  was found to be -742.24 kJ mol^-1. The magnitude of $\Delta H_{298}$  for the reaction

            $N{H}_{2}C{N}_{\left(S\right)}+\frac{3}{2}{O}_{2\left(g\right)}\to N_{2\left(g\right)}+O_{2\left(g\right)}+H_2{O}_{\left(I\right)}is$ ------------- kJ. (Rounded off to the nearest integer)

[Assume ideal gases and R = 8.314 J mol^-1 K^-1]