According to Le Chatelier's principle,which of the following factors influence a chemical system?

How will an increase in pressure affect the following equilibrium? $C_{(s)} + H_2O_{(g)} \rightleftharpoons CO_{(g)} + H_{2(g)}$

For the equilibrium reaction $2NO \rightleftharpoons N_2 + O_2 + x \, cal$,which condition is suitable for the greater dissociation of $NO$?

The equilibrium $Cr_2O_7^{2-} + H_2O \rightleftharpoons 2CrO_4^{2-} + 2H^{+}$ is shifted to the right in:

Aqueous solution of ferric nitrate when mixed with aqueous solution of potassium thiocyanate gives a red coloured solution. The intensity of the red colour becomes constant upon attaining equilibrium. Choose the correct statement when the following chemicals are added to the above solution at equilibrium:
$I$. Oxalic acid
$II$. Mercuric chloride

The role of a catalyst in a reversible reaction is to