For the reaction $N_2O_{4(g)} \rightleftharpoons 2NO_{2(g)}$,the concentrations of $N_2O_4$ and $NO_2$ at equilibrium are $4.8 \times 10^{-2} \, mol \, L^{-1}$ and $1.2 \times 10^{-2} \, mol \, L^{-1}$ respectively. Calculate the value of $K_c$.

• A
  $3 \times 10^{-3} \, mol \, L^{-1}$
• B
  $3 \times 10^{-4} \, mol \, L^{-1}$
• C
  $3.3 \times 10^{-2} \, mol \, L^{-1}$
• D
  $3 \times 10^{-1} \, mol \, L^{-1}$