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

The vapour density of $\mathrm{N}_2 \mathrm{O}_4$ in $\mathrm{N}_2 \mathrm{O}_4 \rightleftharpoons 2 \mathrm{NO}_2$ is 40 . The degree of dissociation is

What is the equilibrium constant $\left(K_C\right)$ for the given reaction?

$$ \mathrm{N}_2+\mathrm{O}_2 \rightleftharpoons 2 \mathrm{NO} $$

Where the equilibrium concentration of $\mathrm{N}_2, \mathrm{O}_2$ and NO are found to be $4 \times 10^{-3}, 3 \times 10^{-3}$ and $3 \times 10^{-3} \mathrm{M}$ respectively.