For the following reaction,the equilibrium constant $K_{c}$ at $298 \ K$ is $1.6 \times 10^{17}$.
$Fe^{2+}_{(aq)} + S^{2-}_{(aq)} \rightleftharpoons FeS_{(s)}$
When equal volumes of $0.06 \ M \ Fe^{2+}_{(aq)}$ and $0.2 \ M \ S^{2-}_{(aq)}$ solutions are mixed,the equilibrium concentration of $Fe^{2+}_{(aq)}$ is found to be $Y \times 10^{-17} \ M$. The value of $Y$ is. . . . .

$A$ solid $XY$ kept in an evacuated sealed container undergoes decomposition to form a mixture of gases $X$ and $Y$ at temperature $T$. The equilibrium pressure is $10 \, bar$ in the vessel. $K_p$ for this reaction is

$X_{2(g)} + Y_{2(g)} \rightleftharpoons 2Z_{(g)}$
$X_{2(g)}$ 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).

$37.8 \ g$ $N_2O_5$ was taken in a $1 \ L$ reaction vessel and allowed to undergo the following reaction at $500 \ K$:
$2N_2O_{5(g)} \rightarrow 2N_2O_{4(g)} + O_{2(g)}$
The total pressure at equilibrium was found to be $18.65 \ bar$. Then,$K_p = \text{ . . . . . . } \times 10^{-2}$ [nearest integer].
Assume $N_2O_5$ to behave ideally under these conditions.
Given: $R = 0.082 \ bar \ L \ mol^{-1} \ K^{-1}$

The equilibrium constant of a reaction at $298 \ K$ is $5 \times 10^{-3}$ and at $1000 \ K$ is $2 \times 10^{-5}$. What is the sign of $\Delta H$ for the reaction?

In a chemical reaction $A + 2B \rightleftharpoons 2C + D$,the initial concentration of $B$ was $1.5$ times of $A$ but the equilibrium concentrations of $A$ and $B$ were found to be equal. The equilibrium constant $(K)$ for the aforesaid chemical reaction is