c
\(\begin{gathered}
\frac{{\text{1}}}{{\text{2}}}{N_{2(g)}} + \frac{3}{2}{H_{2(g)}} \to N{H_{3(g)}};\,\,\Delta H - 46\,kJ\,mol \hfill \\
\Delta H = \frac{1}{2}{(B.E.)_{{N_2}}} + \frac{3}{2}{(B.E.)_{{H_2}}} - 3{(B.E.)_{N - H}} \hfill \\
- 46 = \frac{1}{2} \times ( + 712) + \frac{3}{2} \times ( + 436) - 3 \times {(B.E.)_{N - 1}} \hfill \\
\therefore \,\,3 \times (B.E.)N - H = 356 + 654 + 46 \hfill \\
{(B.E.)_{N - H}} = \frac{{1056}}{3} = 352\,kJ\,mo{l^{ - 1}} \hfill \\
\end{gathered} \)