For the reaction $A + B \rightleftharpoons C + D$ at $250^\circ C$ in a $1 \ L$ vessel,the initial concentration of $A$ is $3$ and $B$ is $n$. If the equilibrium concentration of $C$ is equal to the equilibrium concentration of $B$,what is the equilibrium concentration of $D$?

At $1000 \ K$,the equilibrium constant for the reaction $CO_{2(g)} + H_{2(g)} \rightleftharpoons CO_{(g)} + H_2O_{(g)}$ is $0.53$. In a one litre vessel,at equilibrium the mixture contains $0.25 \ mole$ of $CO$,$0.5 \ mole$ of $CO_2$,$0.6 \ mole$ of $H_2$ and $x \ moles$ of $H_2O$. The value of $x$ is

At $473 \ K$,the equilibrium constant $K_{c}$ for the decomposition of phosphorus pentachloride is $8.3 \times 10^{-3}$. If the decomposition is depicted as:
$PCl_{5(g)} \longleftrightarrow PCl_{3(g)} + Cl_{2(g)} \quad \Delta_{r}H^{\circ} = 124.0 \ kJ \ mol^{-1}$
$(a)$ Write an expression for $K_{c}$ for the reaction.
$(b)$ What is the value of $K_{c}$ for the reverse reaction at the same temperature?
$(c)$ What would be the effect on $K_{c}$ if:
$(i)$ more $PCl_{5}$ is added?
$(ii)$ pressure is increased?
$(iii)$ the temperature is increased?

For the reaction $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$,the value of $K_c$ at $440 \ ^oC$ is $50$. If the reaction is initiated in a $1 \ L$ flask with $1 \ mol$ of $H_2$,$2 \ mol$ of $I_2$,and $3 \ mol$ of $HI$,then the equilibrium concentration of $HI$ will be .......... $M$.

One mole of $H_2O$ and one mole of $CO$ are taken in a $10 \ L$ vessel and heated to $725 \ K$. At equilibrium,$40 \%$ of water (by mass) reacts with $CO$ according to the equation:
$H_2O_{(g)} + CO_{(g)} \longleftrightarrow H_{2(g)} + CO_{2(g)}$
Calculate the equilibrium constant $(K_c)$ for the reaction.

Calculate:
$(a)$ $\Delta G^{\circ}$ and
$(b)$ the equilibrium constant for the formation of $NO_2$ from $NO$ and $O_2$ at $298 \, K$
$NO_{(g)} + 1/2 O_{2(g)} \longleftrightarrow NO_{2(g)}$
Given:
$\Delta G^{\circ}_f(NO_2) = 52.0 \, kJ/mol$
$\Delta G^{\circ}_f(NO) = 87.0 \, kJ/mol$
$\Delta G^{\circ}_f(O_2) = 0 \, kJ/mol$