In a $1 \ L$ closed container,$4 \ moles$ of $PCl_5$ are heated. If $80\%$ of $PCl_5$ remains undissociated at equilibrium,what is the value of the equilibrium constant $(K_c)$?

At $1127 \, K$ and $1 \, atm$ pressure,a gaseous mixture of $CO$ and $CO_2$ in equilibrium with solid carbon has $90.55 \%$ $CO$ by mass.
$C_{(s)} + CO_{2(g)} \longleftrightarrow 2CO_{(g)}$
Calculate $K_c$ for this reaction at the above temperature.

$1.1 \ mol$ of $A$ are mixed with $2.2 \ mol$ of $B$ and the mixture is kept in a $1 \ L$ vessel till the equilibrium is established in the reaction. If the molar concentration of $C$ at the equilibrium point is $0.2 \ M$,then find the value of the equilibrium constant $(K_c)$ for the reaction: $A + 2B \rightleftharpoons 2C + D$

If ${K_c}$ is the equilibrium constant for the formation of $NH_3$,the dissociation constant of ammonia under the same temperature will be

$2 \ mol$ of $N_2$ is mixed with $6 \ mol$ of $H_2$ in a closed vessel of $1 \ L$ capacity. If $50\%$ of $N_2$ is converted into $NH_3$ at equilibrium,the value of $K_c$ for the reaction $N_{2(g)} + 3H_{2(g)} \rightleftharpoons 2NH_{3(g)}$ is

$18.4 \ g$ of $N_2O_4$ was placed in a $1 \ L$ vessel at $400 \ K$ and allowed to attain the following equilibrium: $N_2O_{4(g)} \rightleftharpoons 2NO_{2(g)}$. If the total pressure at equilibrium was $10.64 \ bar$,the approximate $K_p$ is (Given: $R = 0.083 \ L \ bar \ K^{-1} \ mol^{-1}$,assume $N_2O_4$ and $NO_2$ behave as ideal gases).