In reaction $A + 2B \rightleftharpoons 2C + D$,the initial concentration of $B$ was $1.5$ times that of $[A]$,but at equilibrium,the concentrations of $A$ and $B$ became equal. The equilibrium constant for the reaction is:

Equilibrium constants for the following reactions are given (pressure in $atm$) for the reactions at $0\,^{\circ}C$. Select the option mentioning the correct order of True $(T)$ or False $(F)$ statements:
$(A) \ A \cdot 6H_2O_{(s)} \rightleftharpoons A \cdot 2H_2O_{(s)} + 4H_2O_{(g)}; \ K_P = 1.6 \times 10^{-11}$
$(B) \ B \cdot 12H_2O_{(s)} \rightleftharpoons B \cdot 7H_2O_{(s)} + 5H_2O_{(g)}; \ K_P = 2.43 \times 10^{-13}$
$(C) \ C \cdot 10H_2O_{(s)} \rightleftharpoons C_{(s)} + 10H_2O_{(g)}; \ K_P = 10^{-30}$
Aqueous tension of $H_2O$ at $0\,^{\circ}C$ is given as $0.76 \ torr$.
$(I)$ The most effective drying agent will be $C_{(s)}$ out of $C_{(s)}$,$B \cdot 7H_2O_{(s)}$,and $A \cdot 2H_2O_{(s)}$.
$(II)$ At $0\,^{\circ}C$,$A \cdot 6H_2O_{(s)}$ and $B \cdot 12H_2O_{(s)}$ will be efflorescent.
$(III)$ If $R.H.$ is less than $100\%$ in a chamber at $0\,^{\circ}C$,then none of the substances can act as deliquescent.

$AB_{3(g)}$ dissociates as:
$AB_3(g) \rightleftharpoons AB_2(g) + \frac{1}{2}B_2(g)$
When the initial pressure of $AB_3$ is $800 \ torr$ and the total pressure developed at equilibrium is $900 \ torr$,what fraction of $AB_{3(g)}$ is dissociated? .....$\%$

For the reaction $2A_{(g)} + B_{(g)} \rightleftharpoons 3C_{(g)} + D_{(g)}$,two moles each of $A$ and $B$ were taken into a $1 \ L$ flask. Which of the following must always be true when the system attains equilibrium?

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.

What is heterogeneous equilibrium? Give its types with examples.