For the reaction equilibrium, <br> $N_2O_4 (g) \rightleftharpoons 2 NO(g)$ <br> the concentrations of $N_2O_4$ and $NO_2$ at equilibrium are $4.8 \times 10^{-2}$ and $1.2 \times 10^{-2} mol L^{-1}$ respectively. The value of $K_c$ for the reaction is :

Question

( A ) $3 \times 10^{3} mol\;L^{-1}$
( B ) $3 \times 10^{-3} mol\;L^{-1}$
( C ) $3 \times 10^{-1} mol\;L^{-1}$
( D ) $3.3 \times 10^{2} mol\;L^{-1}$