For the reaction N2O4(g)⇌2NO2(g) at 298K (Kc=0.21), a sealed vessel is initially at equilibrium. A small quantity of NO2 is then injected instantaneously, raising the concentration of NO2 while leaving that of N2O4 unchanged at that moment.
Which of the following best describes the immediate effect on the reaction quotient Qc and the resulting net shift?
a) Qc<Kc; the system will shift toward NO2. (product side)
b) Qc=Kc; the system will remain at equilibrium.
c) Qc>Kc; the system will shift toward N2O4. (reactant side)
d) Qc>Kc; the system will shift toward NO2. (product side)