For the simple decomposition reaction AB(g) → A(g) + B(g) rate = k[AB]2 and k = 0.20 L/mol·s. If the initial concentration of AB is 1.50 M, what is [AB] after 12.9 s?
a) 0.072M
b) 0.100M
c) 0.150M
d) 0.200M