50.0 g of N
2O
4 is introduced into an evacuated 2.00 L vessel and allowed to come to equilibrium with its decomposition product, N
2O
4(g)

2NO
2(g). For this reaction K
c = 0.133. Once the system has reached equilibrium, 5.00 g of NO
2 is injected into the vessel, and the system is allowed to equilibrate once again. Calculate the mass of N
2O
4 in the final equilibrium mixture.
◦ 39.5 g
◦ 35.3 g
◦ 30.3 g
◦ 25.2 g
◦ 43.7 g