Which of the following equations is incorrect?

For the reaction $2A_{(g)} + B_{(g)} \rightleftharpoons 3C_{(g)} + D_{(g)}$,$2 \ mol$ each of $A$ and $B$ are taken in a flask. Which of the following will always be true when the system reaches equilibrium?

If $8 \, \text{mol}$ of $PCl_5$ is heated in a closed vessel of $10 \, L$ capacity and $25\%$ of it dissociates into $PCl_3$ and $Cl_2$ at equilibrium,then the value of $K_p$ is .....

The reaction quotient $Q_{C}$ is useful in predicting the direction of the reaction. Which of the following is incorrect?

$A$ mixture of $1.57 \ mol$ of $N_2$,$1.92 \ mol$ of $H_2$ and $8.13 \ mol$ of $NH_3$ is introduced into a $20 \ L$ reaction vessel at $500 \ K$. At this temperature,the equilibrium constant,$K_c$ for the reaction $N_{2(g)} + 3H_{2(g)} \longleftrightarrow 2NH_{3(g)}$ is $1.7 \times 10^2$. Is the reaction mixture at equilibrium? If not,what is the direction of the net reaction?

When the reaction $A + 2B \rightleftharpoons 2C + D$ was studied,it was observed that the initial concentration of $B$ was $1.5$ times that of $A$,and the equilibrium concentrations of $A$ and $C$ were equal. Then $K_C$ for the given equilibrium is equal to