For a reversible reaction $A \rightleftharpoons B$, pre-exponential factor is same for both the forward and backward reactions and has value of $20 \mathrm{~S}^{-1}$. If the enthalpy change along the forward reaction is $-41.5 \mathrm{~kJ} / \mathrm{mol}$, the value of equilibrium constant at 500 K is

For a given equilibrium reaction, addition of inert argon gas at constant volume can shift the equilibrium in

$$ \mathrm{N}_2(g)+3 \mathrm{H}_2(g) \rightleftharpoons 2 \mathrm{NH}_3(g) $$

For the given equilibrium reaction

$$ \mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{~g}) $$

Choose the correct equation to calculate $K_p$.

Aqueous solution of ferric nitrate when mixed with aqueous solution of potassium thiocyanate gives red colour solution. The intensity of red colour becomes constant on attaining equilibrium.

Choose the correct statement when the following chemical is added to the above solution at equilibrium.

I. Oxalic acid

II. Mercuric chloride