The elementary reversible reaction:

$2AB$

is carried out isothermally and isobarically in a flow reactor where pure A is fed at a concentration of

$4\mathrm{.}0mo\frac{l}{d}{m}^3.$ If the equilibrium conversion is found to be $60\%$

$($a$)$ What is the equilibrium constant, $K_C,$ if the reaction is a gas phase reaction?

$($b$)$ What is the $K_C$ if the reaction is a liquid$-$phase reaction?