Calculating the Equilibrium Constant Kc

Consider the following chemical equilibrium reaction at a given temperature:

N2(g) + 3H2(g) <=> 2NH3(g)

In an experiment, a 1.00 L container is charged with 1.00 mol of nitrogen gas and 3.00 mol of hydrogen gas. After reaching equilibrium, the concentration of ammonia is found to be 0.20 M. What is the equilibrium constant (Kc) for this reaction at the given temperature?