For the reaction $2\text{NF}_3(g) \rightarrow 2\text{N}(g) + 6\text{F}(g)$ the standard enthalpy change is $\Delta H^{\circ} = +1668\,\text{kJ}$. Calculate the bond energy of the N-F bond.
- A$-556\,\text{kJ mol}^{-1}$
- B$-278\,\text{kJ mol}^{-1}$
- C$+278\,\text{kJ mol}^{-1}$
- D$+556\,\text{kJ mol}^{-1}$