The gas-phase reaction 2 A(g) → B(g) occurs in a sealed 1.50 L vessel. The concentration of A drops from 0.800 M to 0.600 M during the first 10.0 s, then from 0.600 M to 0.550 M during the next 10.0 s. Calculate the average rate of formation of B (mol·L⁻¹·s⁻¹) for each 10.0-s interval and state which interval exhibits the faster formation of B.