Consider the following reversible reaction at a particular temperature and pressure,
$\mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_3(\mathrm{~g})$
for which the equilibrium constants in terms of mole fraction $(x)$ and partial pressure $(p)$ are defined as $K_x=\frac{x_{\mathrm{NH}_3}^2}{x_{\mathrm{N}_2} x_{\mathrm{H}_2}^3}$ and $K_P=\frac{p_{\mathrm{NH}_3}^2}{p_{\mathrm{N}_2} p_{\mathrm{H}_2}^3}$, respectively. Let an equilibrium mixture contain 3 mol of $\mathrm{N}_2, 1 \mathrm{~mol}$ of $\mathrm{H}_2$ and 1 mol of $\mathrm{NH}_3\left(K_x=8.33\right)$. Now, keeping the temperature constant, if 5 mol of $\mathrm{N}_2$ are added to this mixture, the correct statement(s) is/are

• Correct answer
  A

  The equilibrium will shift to the left producing more $\mathrm{N}_2$, if the $\mathrm{N}_2$ addition is at constant pressure.
• B

  The equilibrium will shift to the right producing more $\mathrm{NH}_3$, if the $\mathrm{N}_2$ addition is at constant pressure.
• C

  The equilibrium will shift to the left producing more $\mathrm{N}_2$, if the $\mathrm{N}_2$ addition is at constant volume.
• Correct answer
  D

  The equilibrium will shift to the right producing more $\mathrm{NH}_3$, if the $\mathrm{N}_2$ addition is at constant volume.

Hence, the correct answer is options: 'A', 'D'.