$4.5 \text{ moles}$ each of hydrogen and iodine is heated in a sealed $10 \text{ litre}$ vessel. At equilibrium,$3 \text{ moles}$ of $HI$ were found. The equilibrium constant for $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$ is .......

For the reaction $A_{(g)} + B_{(g)} \rightleftharpoons 2 C_{(g)}$; $K_{c} = 4$. If equilibrium concentration of $A_{(g)}$ and $B_{(g)}$ are found to be $0.1 \ M$ and $0.4 \ M$ respectively. Determine equilibrium concentration of $C_{(g)}$. (in $M$)

$2 NOCl_{(g)} \rightleftharpoons 2 NO_{(g)} + Cl_{2(g)}$
In an experiment,$2.0 \ mol$ of $NOCl$ was placed in a $1 \ L$ flask and the concentration of $NO$ after equilibrium was established,was found to be $0.4 \ mol/L$. The equilibrium constant at $30^{\circ} C$ is $....... \times 10^{-4}$.

At $298 \ K$,the $K_c$ of the reaction $Cu(s) + 2Ag^+(aq) \rightleftharpoons Cu^{2+}(aq) + 2Ag(s)$ is $3.0 \times 10^{14}$. In a reaction mixture at a certain temperature,$[Cu^{2+}] = 1.8 \times 10^{-2} \ M$ and $[Ag^+] = 3.0 \times 10^{-9} \ M$. Is this reaction in equilibrium? In which direction will the reaction proceed?

At $T(K)$,$K_c$ for the reaction $A_{2(g)} \rightleftharpoons B_{2(g)}$ is $99.0$. Two moles of $A_{2(g)}$ were heated to $T(K)$ in a $1 \ L$ closed flask to reach the above equilibrium. What are the concentrations (in $mol \ L^{-1}$) of $A_{2(g)}$ and $B_{2(g)}$ respectively at equilibrium?

Concentration of a gas is expressed in which of the following terms in the calculation of the equilibrium constant?