To solve this problem, we need to understand the stoichiometry of the Haber process.$\newline$The balanced chemical equation for the Haber process is:$\newline N_2 + 3H_2 \rightarrow 2NH_3 \newline$Explanation:$\newline$• According to the balanced equation, 1 mole of $N_2$ reacts with 3 moles of $H_2$ to produce 2 moles of $NH_3. \newline$• We need to find the number of moles of $H_2$ required to produce 20 moles of $NH_3. \newline$Using the stoichiometric ratio from the balanced equation:$\newline \frac{3 \ moles \ of \ H_2}{2 \ moles \ of \ NH_3} \newline$Set up the proportion:$\newline \frac{3 \ moles \ of \ H_2}{2 \ moles \ of \ NH_3} = \frac{x \ moles \ of \ H_2}{20 \ moles \ of \ NH_3} \newline$Cross-multiply to solve for $x: \newline 3 \times 20 = 2 \times x \newline 60 = 2x \newline x = \frac{60}{2} \newline x = 30 \newline$Therefore, 30 moles of hydrogen molecules are required to produce 20 moles of ammonia.$\newline$This corresponds to Option 3.