Partial pressures (in atm) for the reaction N2O4(g)⇌2NO2(g) were recorded as follows:
Time (s): 0 10 20 30 40
PN2O4: 0.80 0.60 0.53 0.52 0.52
PNO2: 0.00 0.30 0.54 0.55 0.55
At which recorded time has the system most likely reached equilibrium?
a) 20 \text{ s}
b) 30 \text{ s}
c) 10 \text{ s}
d) 40 \text{ s}