$8 \ mol$ of $AB_{3(g)}$ are introduced into a $1.0 \ dm^3$ vessel. If it dissociates as $2AB_{3(g)} \rightleftharpoons A_{2(g)} + 3B_{2(g)}$. At equilibrium,$2 \ mol$ of $A_2$ are found to be present. The equilibrium constant of this reaction is

At $700 \, K$,the equilibrium constant for the reaction $H_{2(g)} + I_{2(g)} \longleftrightarrow 2 HI_{(g)}$ is $54.8$. If $0.5 \, mol \, L^{-1}$ of $HI_{(g)}$ is present at equilibrium at $700 \, K$,what are the concentrations of $H_{2(g)}$ and $I_{2(g)}$,assuming that we initially started with $HI_{(g)}$ and allowed it to reach equilibrium at $700 \, K$?

For the reaction $PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)}$,at equilibrium,the mole fraction of $PCl_5$ is $0.4$ and the mole fraction of $Cl_2$ is $0.3$. What will be the mole fraction of $PCl_3$?

$5 \ moles$ of $SO_2$ and $5 \ moles$ of $O_2$ are allowed to react. At equilibrium,it was found that $60\%$ of $SO_2$ is used up. If the partial pressure of the equilibrium mixture is $1 \ atm$,the partial pressure of $O_2$ is (in $atm$)

Match the items in List-$X$ with List-$Y$ and select the correct option.

List-$X$	List-$Y$
$(A)$ $A_{(g)} \rightleftharpoons B_{(g)} + \text{Heat}$	$(i)$ Equilibrium constant
$(B)$ $r_b/r_f$	$(ii)$ Favored at low temperature
$(C)$ $r_f/r_b$	$(iii)$ [Equilibrium constant]$^{-1}$
$(D)$ $2A_{(g)} + B_{(g)} \rightleftharpoons C_{(g)}$	$(iv)$ $A_{(g)} + B_{(g)} \rightleftharpoons C_{(g)} + D_{(g)}$
$(E)$ Effect of pressure	$(V)$ $\Delta n < 0$

The equilibrium constant at $298 \ K$ for a reaction $A + B \rightleftharpoons C + D$ is $100$. If the initial concentration of all the four species were $1 \ M$ each,then the equilibrium concentration of $D$ (in $mol \ L^{-1}$) will be: