# Consider the reaction $N_2 + 3H_2 \rightarrow 2NH_3$ carried out at constant temperature and pressure. If $\Delta H\: and\: \Delta U$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?
$\begin {array} {1 1} (A)\;\Delta H > \Delta U & \quad (B)\;\Delta H < \Delta U \\ (C)\;\Delta H = \Delta U & \quad (D)\;\Delta = 0 \end {array}$