How is the direction of a reaction predicted?

The equilibrium of formation of phosgene is represented as:
$CO_{(g)} + Cl_{2(g)} \rightleftharpoons COCl_{2(g)}$
The reaction is carried out in a $500 \ mL$ flask. At equilibrium,$0.3 \ mol$ of phosgene,$0.1 \ mol$ of $CO,$ and $0.1 \ mol$ of $Cl_2$ are present. The equilibrium constant $(K_c)$ of the reaction is:

$5 \ moles$ each of $H_2$ and $I_2$ were heated in a sealed $10 \ L$ vessel. At equilibrium,$2 \ moles$ of $HI$ were found. The equilibrium constant for the reaction $H_{2(g)} + I_{2(g)} \rightleftharpoons 2HI_{(g)}$ is:

Give the equilibrium constant expression for the following reactions:
$(a)$ $Ni_{(s)} + 4CO_{(g)} \rightleftharpoons Ni(CO)_{4_{(g)}}$
$(b)$ $Ag_{2}O_{(s)} + 2HNO_{3_{(aq)}} \rightleftharpoons 2AgNO_{3_{(aq)}} + H_{2}O_{(l)}$

In a chemical equilibrium $A + B \rightleftharpoons C + D$,when $1 \, mol$ each of two reactants are mixed,$0.5 \, mol$ each of the products are formed. The equilibrium constant is

What is the equilibrium constant $(K_C)$ for the given reaction?
$N_2 + O_2 \rightleftharpoons 2 NO$
Where the equilibrium concentrations of $N_2$,$O_2$ and $NO$ are found to be $4 \times 10^{-3} \ M$,$3 \times 10^{-3} \ M$ and $3 \times 10^{-3} \ M$ respectively.