The unit of equilibrium constant $K$ for the reaction $A + B \rightleftharpoons C$ would be

The following concentrations were observed at $500 \ K$ for the formation of $NH_3$ from $N_2$ and $H_2$. At equilibrium: $[N_2] = 2 \times 10^{-2} \ M$,$[H_2] = 3 \times 10^{-2} \ M$ and $[NH_3] = 1.5 \times 10^{-2} \ M$. The equilibrium constant for the reaction is:

For the reaction $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$,the equilibrium constant $K_p$ is $16$. If the volume of the container is reduced to $\frac{1}{2}$ of its original value,what will be the value of $K_p$ at the same temperature?

The reaction,$2A_{(g)} + B_{(g)} \rightleftharpoons 3C_{(g)} + D_{(g)}$ is begun with the concentrations of $A$ and $B$ both at an initial value of $1.00 \ M$. When equilibrium is reached,the concentration of $D$ is measured and found to be $0.25 \ M$. The value for the equilibrium constant for this reaction is given by the expression:

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

Explain the reaction quotient and how it is used to predict the direction of a reaction.