Dinitrogentetraoxide Partially Decomposes According to the Following Equilibrium

Dinitrogentetraoxide partially decomposes according to the following equilibrium:
N₂O₄ (g) -2NO₂ (g)
A 1) 000- L flask is charged with 3.00 × 10^{- 2} mol of N₂O₄. At equilibrium, 2.36 × 10^{- 2} mol of N₂O₄ remains. K_eq for this reaction is .

A) 0.391
B) 0.723
C) 6.93 × 10^{- 3}
D) 1.92 × 10^{- 4}
E) 0.212