$N_2 + 3H_2 \longrightarrow 2NH_3$ This reaction is carried out at constant temperature and pressure. If $\Delta H$ and $\Delta U$ are enthalpy and internal energy change for the reaction, which of the following expression is true?

Question

(a) $\Delta H = 0$
(b) $\Delta H = \Delta U$
(c) $\Delta H < \Delta U$
(d) $\Delta H > \Delta U$