The rate of disappearance of hydrogen \((\text{H}_2)\) from the reaction
\[
\text{N}_2(g) + 3\text{H}_2(g) \rightarrow 2\text{NH}_3(g)
\]
is \(6\, \text{g L}^{-1}\text{s}^{-1}\). The rate of production of ammonia \((\text{NH}_3)\) in \(\text{g L}^{-1}\text{s}^{-1}\) is: