In the reaction $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$,the equilibrium concentrations of $PCl_5$ and $PCl_3$ are $0.4 \ mol/L$ and $0.2 \ mol/L$ respectively. If the value of $K_c$ is $0.5$,what is the concentration of $Cl_2$ in $mol/L$?

$K_1, K_2$ and $K_3$ are the equilibrium constants of the following reactions $(I), (II)$ and $(III)$ respectively.
$(I) \, N_2 + 2O_2 \rightleftharpoons 2NO_2$
$(II) \, 2NO_2 \rightleftharpoons N_2 + 2O_2$
$(III) \, NO_2 \rightleftharpoons \frac{1}{2} N_2 + O_2$
The correct relation from the following is

Given that the equilibrium constant for the reaction,$2SO_{2(g)} + O_{2(g)} \rightleftharpoons 2SO_{3(g)}$ has a value of $278$ at a particular temperature. What is the value of the equilibrium constant for the following reaction at the same temperature? $SO_{3(g)} \rightleftharpoons SO_{2(g)} + \frac{1}{2} O_{2(g)}$

Consider the following gaseous equilibrium reactions $(I)$,$(II)$ and $(III)$ with equilibrium constants $K_1$,$K_2$ and $K_3$ respectively:
$I$) $\frac{1}{2} N_2 + \frac{3}{2} H_2 \rightleftharpoons NH_3$
$II$) $2 NO \rightleftharpoons N_2 + O_2$
$III$) $H_2 + \frac{1}{2} O_2 \rightleftharpoons H_2 O$
The correct expression for the equilibrium constant for the gaseous equilibrium reaction $2 NH_3 + \frac{5}{2} O_2 \rightleftharpoons 2 NO + 3 H_2 O$ is

What is the equilibrium expression for the reaction $P_{4(s)} + 5O_{2(g)} \rightleftharpoons P_4O_{10(s)}$?

For the reaction $cis-C_2H_2Cl_2 \rightleftharpoons trans-C_2H_2Cl_2$,the equilibrium constant at $500 \ K$ is $0.6$. The equilibrium constant for the reaction $trans-C_2H_2Cl_2 \rightleftharpoons cis-C_2H_2Cl_2$ at the same temperature will be ...............