Select the incorrect statement $(s)$ regarding the state of equilibrium.

Which of the following is not a characteristic property of chemical equilibrium?

For the reaction ${H_2} + {I_2} \rightleftharpoons 2HI$ at $721 \ K$,the value of the equilibrium constant is $50$. If $0.5 \ mol$ of each of ${H_2}$ and ${I_2}$ are added to the system,the value of the equilibrium constant will be .............

Predict which of the following reactions will have an appreciable concentration of both reactants and products:
$(a)$ $Cl_{2(g)} \longleftrightarrow 2Cl_{(g)};$ $K_{c}=5 \times 10^{-39}$
$(b)$ $Cl_{2(g)}+2NO_{(g)} \longleftrightarrow 2NOCl_{(g)};$ $K_{c}=3.7 \times 10^{8}$
$(c)$ $Cl_{2(g)}+2NO_{2(g)} \longleftrightarrow 2NO_{2}Cl_{(g)};$ $K_{c}=1.8$

When two reactants $A$ and $B$ are mixed to form products $C$ and $D$,what is the value of the reaction quotient $Q$ at the initial state of the reaction?

Explain the dynamic nature of a chemical system in the laboratory using an activity.