For the formation of $NH_{3(g)}$ from its constituent elements,which of the relations between the reaction quotient $(Q)$ and equilibrium constant $(K_C)$ is correct for the backward reaction?

If the equilibrium constant for the reaction $A + 3B \rightleftharpoons 2C$ is $K_1$,then the equilibrium constant $K_2$ for the reaction $2C \rightleftharpoons A + 3B$ should be:

The equilibrium constant,$K_c$ for $3 C_2H_{2(g)} \rightleftharpoons C_6H_{6(g)}$ is $4 \, L^2 \, mol^{-2}$. If the equilibrium concentration of benzene is $0.5 \, mol \, L^{-1}$,the equilibrium concentration of acetylene in $mol \, L^{-1}$ is:

$PCl_5 \rightleftharpoons PCl_3 + Cl_2$. If the equilibrium constant $(K_C)$ for the above reaction at $500 \ K$ is $1.79$ and the equilibrium concentrations of $PCl_5$ and $PCl_3$ are $1.41 \ M$ and $1.59 \ M$,respectively,then the concentration of $Cl_2$ is approximately: (in $M$)

The value of $K_{c}$ for the reaction $2 A \rightleftharpoons B + C$ is $2 \times 10^{-3}$. At a given time,the composition of the reaction mixture is $[ A ] = [ B ] = [ C ] = 3 \times 10^{-4} \ M$. In which direction will the reaction proceed?

The equilibrium constant for the given reaction is $100$.
$N_{2(g)} + 2 O_{2(g)} \rightleftharpoons 2 NO_{2(g)}$
What is the equilibrium constant for the reaction given below?
$NO_{2(g)} \rightleftharpoons \frac{1}{2} N_{2(g)} + O_{2(g)}$