Steam reacts with iron at high temperature to give hydrogen gas and $Fe_3O_{4(s)}$. The correct expression for the equilibrium constant is

At $490\,^{\circ}C$,the equilibrium constant for the synthesis of $HI$ is $50$. The value of $K$ for the dissociation of $HI$ will be:

Consider the following equilibrium reaction in gaseous state at $T(K)$.
$A(g) + 2B(g) \rightleftharpoons 2C(g) + D(g)$
The initial concentration of $B$ is $1.5$ times that of $A$. At equilibrium,the concentrations of $A$ and $B$ are equal. The equilibrium constant for the reaction is

For the reaction $2 SO_2 + O_2 \rightleftharpoons 2 SO_3$,the units of $K_c$ are

At $400 \ K$ in a closed vessel,the reaction $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$ takes place. At equilibrium,the concentration of $H_2$ is $0.6 \ mol \ L^{-1}$,the concentration of $I_2$ is $0.8 \ mol \ L^{-1}$,and the concentration of $HI$ is $0.14 \ mol \ L^{-1}$. Calculate the equilibrium constant $(K_c)$.

At a definite temperature,the $K_c$ of the following reaction is $0.18$: $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$. In a reaction mixture at the same temperature,$[PCl_3] = 0.042 \ M$,$[Cl_2] = 0.024 \ M$,and $[PCl_5] = 0.005 \ M$. Is this reaction in equilibrium? In which direction will the reaction proceed?