$2NOBr_{(g)} \rightleftharpoons 2NO_{(g)} + Br_{2_{(g)}}$. If $NOBr$ is $40\%$ dissociated at a certain temperature and a total pressure of $0.30 \text{ atm}$,the $K_p$ for the reaction $2NO_{(g)} + Br_{2_{(g)}} \rightleftharpoons 2NOBr_{(g)}$ is:

Which of the following statements is/are true about equilibrium?
$(a)$ Equilibrium is possible only in a closed system at a given temperature.
$(b)$ All the measurable properties of the system remain constant at equilibrium.
$(c)$ Equilibrium constant for the reverse reaction is the inverse of the equilibrium constant for the reaction in the forward direction.

Consider a reversible reaction $2A + B \rightleftharpoons 2C$ having equilibrium constant $K_c = 25$. If a reaction vessel contains $2 \ mol$ of $A$,$0.25 \ mol$ of $B$,and $0.5 \ mol$ of $C$ in a $100 \ L$ vessel,what will be the direction of the reaction?

$X_{2(g)} + Y_{2(g)} \rightleftharpoons 2Z_{(g)}$
$X_{2(g)}$ and $Y_{2(g)}$ are added to a $1 \ L$ flask and it is found that the system attains the above equilibrium at $T \ K$ with the number of moles of $X_{2(g)}$, $Y_{2(g)}$ and $Z_{(g)}$ being $3$, $3$ and $9 \ mol$ respectively (equilibrium moles). Under these conditions of equilibrium, $10 \ mol$ of $Z_{(g)}$ is added to the flask and the temperature is maintained at $T \ K$. Then the number of moles of $Z_{(g)}$ in the flask when the new equilibrium is established is . . . . . . . (Nearest integer).

At $550 \ K$,the $K_c$ for the following reaction is $10^4 \ mol^{-1} \ L$: $X_{(g)} + Y_{(g)} \rightleftharpoons Z_{(g)}$. At equilibrium,it was observed that $[X] = \frac{1}{2}[Y] = \frac{1}{2}[Z]$. What is the value of $[Z]$ (in $mol \ L^{-1}$) at equilibrium?

In the reaction $PCl_5 \rightleftharpoons PCl_3 + Cl_2$,one mole of $PCl_5$ is started in a $5 \ L$ vessel. If $0.3 \ mol$ of $PCl_5$ is present at equilibrium,find the concentration of $PCl_3$,total moles,and the value of $K_c$.