A reaction A B is carried out isothermally in 50-L constant-volume batch reactor. Ten moles of pure A are initially placed in the reactor. The reactor is well mixed. Assuming that the rate law is -rA= kCA1.5 with k = 0.865 (L/mol)0.5s-1, calculate the time necessary to reduce the number of moles of A in the reactor to 1 mole