Two neutral species, A and B, with diameters 442 pm and 885 pm, respectively, undergo the diffusion-controlled

Question:

Two neutral species, A and B, with diameters 442 pm and 885 pm, respectively, undergo the diffusion-controlled reaction A + B --7 P in a solvent of viscosity 1.27 cP at20°C. Calculate the initial rate d [P]/dt if the initial concentrations of A and Bare 0.200 mol dm-3 and 0.150 mol dm3 respectively.